Thanks, now I was able to log in, and found the problem.
So, the only difference between how the two versions load their scripts is, that in the Lite version the ‘jquery’ requirement is missing from the wp_register_script(..) call. It is actually a bug in the current Lite version, which is about to be fixed in the upcoming release.
Since this was the only difference, I checked if there was a custom jQuery script loaded within the theme functions.php file, and there was, but the new handler name was incorrect, it was in camel-case instead of lower-case: https://i.imgur.com/5inG0x9.png
I have corrected that to lower case via the theme editor on the back-end, now it should be working. Many other plugins also use that as a pre-requesite string, and WordPress is case sensitive to that, so those scripts won’t load. Now I am seeing some other scripts loading as well, which weren’t there before. It should be all right now.