What about those custom profiles ???
Well. what do you want me to say?
IF you have working print or filament profiles then please export them into a folder you find later on.
It also helps to copy the corresponding folders on your drive, those in the user folders.
Like with so many things it is not always easy to transfer things from one Studio version to a much later one.
It can and might happen that you exported your profiles and that the import in the same Studio version works fine but trying the same with a Studio version a few levels up can mean prints fail or that profiles fail to show up.
Sometimes you can force this to somewhat work by corrupting the installed Studio version (like by deleting a few vital files) and installing over that version.
When the installer (or if) find the error log it should always aim to import whatever was present in the old installation.
If you ever watched the install closely you probably notice that the installer just deletes all files in all folders.
I don’t know it the same still works on Studio versions above 1.9x but you can always try…
Before closing the installer check if your custom profiles are still present in their folders - if not copy them over again!
You get a 50-50 chance that Studio will honour your hard work by having your custom filaments and print setting show up.
What are the downfalls here?
Lets say you had enough but way to late in time …
Means you have profiles for a much later firmware and Studio version that what you intent to downgrade to.
Or in lame words it means you have settings and file structures the old version might not be able to handle (correctly).
Sometimes it works and if it does then be grateful and also export those profiles!
Chances are though that once you double check with older 3MF you have and never ones you create before the downgrade that the prints fail to impress.
If this happens then PLEASE don’t start screaming and swearing like I did for few hours as it won’t help - trust me I know…
And I also know you will hate me for the solutions as it involves a lot of manual labour…
If you exported WORKING profiles you can access them through Notepad++, binary editors and more.
Helps though if you took screenshots of your custom settings, profiles and such.
Trust me when I say that starting from pure scratch after a complete downgrade IS your best option to provide working outcome.
Ok, but what IS the best way to get custom filaments working on the 1.07 firmware and matching Studio version if you don’t use Orca?
Check the Bambu Wiki.
Create a custom profile as the Wiki says but with some minor changes >
Lets say you main filament supplier is ‘AAFilaments’ or in short AA.
You might have 20 different colours of PLA and several types of filaments from AA but you WILL keep things dead simple!
Take a pen and some paper and start writing down notes based on the exported working profiles you had.
For example: AA PLA of the standard kind prints fine at 218ºC a bed temp of 52 and …
Unless you actually have massive fluctuation for different colours just define a single PLA profile for AA that has no colour assigned.
The colour you set in Studio after an AMS sync in the AMS settings.
Similar story for the K-Factors >
Calibrate the filament from scratch if there is any flaws you should not have and save the profile with the number in the filename!
E.g.: AA PLA 0.015, AA PLA 0.22, …
The befit of this approach is that you can use those k-factor setting no matter the filament colour and that you only need one filament profile unless colour like black actually require slight adjustments you don’t want to do on the fly when needed.
For PLA matte, silk or other plastics you use the same approach.
You will quickly get used to this and see the benefit of the simplicity.
Ok, id did all the above, even created the filaments profiles from scratch and in the simple form…
But you ruined it all for me and my 3MF files won’t produce proper prints - damn you!!!
I know… It really sucks if you wasted all the time reading my nonsense only to find out you can’t use your print files…
My apologies but please direct your frustration towards Bambu instead 
Use logic here!
Studio versions change, with that standard setting and we can also find new features.
How would a Studio version know what to do if there is lines it can’t interpret?
Or how could a newer Studio version know that you compensated for flaws in your settings that are now fixed in completely different settings?
You hopefully see the real issue now
So again, try logic >
The model printed fine with the firmware and Studio version it was created with.
So why not just import the model geometry and trust that your current machine and other settings a proper ?
The only thing that really gets lost here is the support setting but that is good if you ask me…
Calibrate your filaments and settings and just import the model geometry - make that a habit for downloaded files.
Custom supports can be a pain but I still find this hassle preferable over importing a file that fails to print no matter what I try.
I downloaded less than 10 3MF until I got fed up with the hassles of syncing the AMS trying to get the filament to match and all that…
Import the geometry, define things as needed and Bob’s your aunty.
I know, it is not what Bambu promises in terms of being easy and hassle free but it beats wasting hours and filament to watch prints fail again and again…