Fatal Error when activating plugins & Import/Export Issues

I’m using the Pro versiona ans after installing the plugin, I get Fatal Error each time I activate any plugin on any site in my multisite installation.

Also, after trying to use the import/export feature which doesn’t work for me, it permanently breaks another one of my plugins.

This is a very good plugin otherwise and I would like to continue using it if these issues can be resolved.

FYI: I do not have the plugin network activated. I’m running PHP 7.3 and the latest version of WP.

Please help.