Why is the IMPORTRANGE formula not working in Google Sheets?

Question

Google Sheets

Good afternoon!
Please help me solve the problem:
There are 50 Google tables (all have full editing access)
I create table No. 51, and using the IMPORTRANEGE () formula I try to get data from these 50 tables. As always, at the first request, I confirm access to the table:

then everything hangs with the inscription "access settings", once it gave the following error:

Please help with the solution.
Thanks in advance!

Answer 1

faced the same problem, it turned out - even if I am the owner of both tables, access will not open, access is possible only if the document is made editable to the entire Internet. This is of course very strange, more like a flaw (bug).

Answer 2

Import works only if both files are in Google format, if XLSX or something else - it will not work.