I’m making a 7 color image print (2" diameter 1/8" thick tags) with the image to keychain. 5 of the colors are ABS, 2 are ASA. One of the ASA colors is from Filamentum, the other from IIIDMax. For some reason, either of those keep not printing. It will change filaments, load the new one, then won’t print on the tower. It runs through the pattern but nothing is being extruded. There are no errors and the temps are within mfg spec. It looks like it printed 1-2 layers of it when the print first started, then it starts not printing them. I can tell because the AMS spools don’t turn, and the hub doesn’t ever signal it to feed more filament. I think the extruder just spins and isn’t actually feeding the filament. Then when it finishes, it’ll change colors and start printing again. I’ve printed lots of other ASAs, just not these 2 brands. Is it a filament problem, or something like a worn extruder? All other filaments print fine, just not these 2.
Ugh. I think it’s a PEBCAP error - Problem Exists Between Chair And Printer. I figured I might as well try and change out the hot end. It’s had multiple broken pieces I’ve had to clean out. So I swapped it with a new one. I was looking at the old one to see if there was some residual partial clogs or something, and realized I still had a .2mm nozzle on there but was running it with the slicer set to .4mm. I was also getting some slightly stringy surfaces on some of the colors, now I know why. I’m leaving this up in case someone else does dumb stuff too. LOL
Isn’t it nice to find the cause of a problem even if there is no one else but yourself to blame for it ? 
For some reason we manage to fool ourselves very easy - been there, done that - many time…
I did that more than once on my last printer.