I am having the same issue (a year later). I'm trying to display a Trombinoscope module on a J4 site, and it will not show up. I don't know if this is specific to Trombinoscope, but I have contacted the developer and after some discussion, he directed me here.
The modules work fine on Joomla 3 using SPPB Version: 3.8.10.
The J4 site is using SPPB version 5.2.6.

