So I think i’ve solved it! Thanks for your help and patience 
I want to do a bit more testing, but when i’m happy i’ll update on the changes I made incase it helps anybody else.
edit:
So I solved the first issue by cutting out numpy, but then I had to find an alternative. I’ve ended up using some code in the trial routine based on the help on this post Dynamically reference the current loop - #8 by RobM except I put mine into the start and end of the routine, rather than start of the experiment.
I also discovered I had errors in my conditions files which was causing issues.
It all seems to work currently, although i’ll keep doing a bit more testing to ensure it’s randomised how I expected.
Thanks for the tips and links, it really helped knowing someone else was on hand!