Import does not seem to be working

Import does not seem to be working

I have started to import my mail from an old account to Zoho. I successfully imported two very small inbox files (zipped files including eml letter files). After that, with larger, main files, I have no success at all, but I also cannot see any error messages or any activity on the import page at all.

I am using Opera browser for this, operation system is Windows 10.
The larger files were 192 Mb and then larger. None of them seem to get any activity going in the browser page.