Last file dissapeared with crash

Yesterday, I opened the app to add some job related expense receipts to a file I build over the course of the month, and send it to my accountant by the end of it.

I have done this for years, with no problem whatsoever.
Today, I opened the app, saw the file there for a couple of seconds, and then boom! It crashed.
When I reopend it, ONLY THAT FILE was missing. Not any other files I have been working on or modifying dissapeared... only my most important one of the month.

I truly do not understand what happened, and the chat support does not know how to handle my situation.

I NEED THIS FILE BACK, PLEASE HELP ME!!!

I went to my iPad, turned off the wi-fi, opened the app, and I saw the file there... of course it wouldn't open (screenshot attached), but I knew as soon I would turn the wi-fi on, it would disappear... it actually did.
The app crashed, and my file was gone.
This is absurd and frustrating... I've been loving this app for years... now I'm considering another option. It's ridiculous!

Thanks for reading.