Can you please try a small change in the code?
In this line here:
→ SuiteCRM/StudioParser.php at master · salesagility/SuiteCRM · GitHub
Add the word static in there, so it becomes:
public static function buildImageButtons($buttons, $horizontal=true)
this should solve the FATAL error in your log, and hopefully won’t break anything else. I have no idea if it will affect your original issue, but it’s worth a try.