Sorry for not following up on After upgrade from Pro 6.2.9. to 6.3.8 font-settings fail to apply within 10 days.
Here is a screenshot with the issue…
Correction on the screenshot: www.eft-center-hannover.de is Pro 6.2.3
I just found out, that if there are two pro versions under the themes folder, one in folder pro and the other in pro.new the version numbers shown on wp-admin/admin.php?page=x-addons-home and on /wp-admin/update-core.php do not match. See next screenshot. /wp-admin/themes.php of course, shows both intances of pro.
We flushed every cache we could find, used several browsers, tried incognito mode. The font issue showed up consistently.
Could the font not applying have to do with that the test sites are copies of the production wp-installs? But then, why does https://eftph-test.eftch.de/ (Pro 6.3.8) as test of https://www.eft-paartherapie-hannover.de/ (also Pro 6.3.8) not have this issue?
Any suggestions on what goes wrong are welcome.