Paht nylon and asa poor layer adhesion as support

Been printing a lot of paht and pa6, recently found an old Bambu forum post with some support settings for using ASA as support interface for nylons and in this case paht CF from Bambu.

Have been using it and the supports are awesome, easy to remove etc

USING GENERIC ASA AND BAMBU PAHT FILAMENT SETTINGS IN ORCA. ELEGOO ASA AND BAMBU PAHT ARE FILAMENT BRANDS

Moved on to printing more mechanical parts and started noticing parts breaking. Upon further investigation it seems the layer adhesion on layers where the ASA has been deployed as interface is what’s affected, snapping at layer lines specifically in those spots with little effort, the other layers that are only printed in nylon are solid

I have played with purge settings thinking maybe some ASA leftover in nozzle gets carried to the paht part. Even at 800 I have the same issue

Could it be different fan settings or temp settings between the two filaments?

Anyone have any ideas of how to fix this or gain some clarity on why it’s happening? I know plenty of people use support interface(ASA or otherwise) for Nylon but this doesn’t seem to be a heavily covered issue online if at all.

I noticed a setting in the slicer that allows for independent layer heights for support interface layers. When using the Bambu-Labs Support Material for PA, it will give you a warning to deselect this setting. The setting notes say this will be automatically disabled when a priming tower is enabled but it does not seem to disable it (or it does not seem to). And perhaps, you have disabled the priming tower and it is not deselected. I have not tested this at all but it may be a good setting to review for your issue.

Mike