Two serious bugs were found so I fixed them yesterday. Ver 2.6.1 including these fixes have been already submitted to Unity. I think it'll be available in a couple of days.
The bugs are as follows.
Compatibility problem with the former version's UModeler Meshes made using UModeler 2.5 or former versions are not loaded using UModeler 2.6 when .unity file is opened. It also means that meshes made with UModeler 2.6 is not compatible with UModeler 2.6.1 and others. If you have been working with UModeler 2.6, please switch to UModeler 2.5 until 2.6.1 is available.
Not displaying transform gizmos and number overlays etc in Unity 2019.1.0f2
I'm sorry for any inconvenience caused by 2.6.