FYI
On Jan 31st iThemes updated the readme.txt with the following change:
+Tested up to: 5.0.3
-Tested up to: 4.9.8
Nothing else changed so no new release yet.
Tested up to doesn’t necessarily mean it is fully compatible with WordPress 5.0.3.
I know for a fact that in the 7.2.0 plugin release the Per Content setting of the SSL module is not compatible with the Block Editor.
(Which by the way was fixed at the start of dec 2018 for the Pro plugin).
To make the free plugin compatible you would need to use the Classic Editor plugin. Information that imho should have been included in the readme.txt as well …