Site content in sp2019 not visible in modern view

I have upgraded a site collection from SP 2013 to SP2019, via SP2016.

The upgraded site has converted successfully and all content is in place.  However the Site Contents page in any and every site shows no content when in Modern view.  If I click on the subsites tab it does show the subsites.

To view the site contents, I have to change back to Classic view.

Any ideas on how to fix this would be appreciated.