In AE 25.1 (and also 25) content of script UI panels often disappear and only AE restart helps to bring it back.
This issue is new to AE 25 and forces me to not use it (AE25), because I use lot of handy scripts with their UI panels.
I attached both states - When it is OK, and after finished render.
Sometimes it dissapear sometimes not.
This bug affects all script UI panels but not affect panels from extensions (like you can see on Kbar on the left)