There's usually a compatibility table from Esri where it tells you which version of ArcGIS Enterprise is compatible with ArcGIS PRO, this is important for geoprocessing tools (Like the printing tool). I discovered this not long ago.
Geoprocessing service compatibility
There is good article from Esri Australia about this:
Compatibility between arcgis desktop applications and arcgis enterprise
In previous versions of Enterprise (10.8.1) I had issues with secure web services when I was using custom templates from ArcGIS PRO. The way I solved the issue was creating an account for the ArcGIS Server service in Portal and adding that account to the groups I needed the tool to print web services (the problem was always that the ArcGIS Server service account, which is in charge of the printing geoprocessing tool, didn't have access to the web services, as those were secure under a group, so that account couldn't access the resource to render and print the layer in the map). Once that account had access, the maps were printing ok (I don't seem to have that issue in ArcGIS Enterprise 11.2).