Just to add what others have said, the temp you dry at is as important if not more important than time and different for each type of plastic. If you don’t have it hot enough (typically near the glass transition temperature of the plastic) then the moisture is not able to escape the plastic.
Cool project as well, I have wanted to do the same!
I know you solved it but for anyone that finds this later this feature/behavior is typically called “NAT Hairpin” in case you are looking for a setting to enable or disable, hope this helps!