OPIM idgn opening problem

Hello, I have problem with opening idgn files with OpenPlant Isometric Manager. I get an error:

[10.01.2020 19:21:38]    Loading 1 i-models
========================================================================================================================
                        Starting i-model engine
                        [19:21:38.3740941]Loading C:\temp\test1.dgn.i.dgn
                        [19:21:40.0768211]Error:
Model not valid

[10.01.2020 19:21:40]    Loaded 0 out of 1 i-models
------------------------------------------------------------------------------------------------------------------------

Im using OPM and OPIM CE Update 6

Anyone had the same problem?