Indeed other topics I created here at this moment are related to the .txt files but I’m taking about the topic I didn’t created but commented in. Here is what I wrote in the topic Files from phone can only be opened inside OO app and not from outside OO app when we choose an option "Open with" regarding the situation with .docx and .xlsx and .pptx files:
‘ONLYOFFICE Sample Spreadsheets.xlsx’ opened from ‘open with other app’ list: app immediately closed after showing ‘Preparing to open’ message window. Another attempt displayed ‘Wanna repair?’ dialogue window, the results of the repair was even quicker exit of the app.
‘ONLYOFFICE Sample Presentation.pptx’ opened from ‘open with other app’ list: same as the previous.
‘ONLYOFFICE Sample Document.docx’ opened from ‘open with other app’ list: the ‘Preparing to open’ message window never disappeared, the OnlyOffice app hunged.
The very same results I’m getting now when opening that files from inside of the app. It looks as the problem with the app handling the cache / the storage. But on Redmi 5 the files were successfully opened from inside of the OnlyOffice app.
But @Anyum already answered, his feedback is a prio.