Ok, thank you, It´s good to know that it´s not some general issue. I will discuss it with colleagues from Tech Support.
Just to be sure - ArcGIS PRO 2.8, PostgreSQL 11, dltsolutions 2.7.1, untools 2.8.1 on Asset Package 2.7 is everything which should work together with Water Management Solution?
If we find a the reason for this/solution I will let you know.
Thank you for you help!
Vladimir