Without knowing your exact code, it looks like you have at least one value/state that causes troubles. But when reloading (session in retool seems to end, in my experience) or opening in another tab (also new session) this value gets "fresh information" and your page/app works.
Maybe this helps you with your search!
Sorry that i couldn't help more! If you have any idea for my problem (or a little time to read), i would appreciate!
http://community.retool.com/t/only-run-if-fails/6964