The UI error message is unrelated to your problem. It's coming from the Substance Source plugin which is now deprecated. We recommend to remove it and use the Substance Launcher instead or the Substance Source website.
According to your log file, the Substance Painter's shelf takes a bit more than 2 minutes to be discovered (123s). Until resources are discovered on the disk, they won't appear in the UI. 2 minutes is very long, on an SSD this step should take maximum 10 seconds if not less. On which type of hard drive is Substance Painter installed ?
The freeze/loading when opening the Smart Materials/Smart Masks mini-shelf/shelf preset is expected however. The freeze is related to the fact when look into the file to load information (metadata, thumbnail, etc.) and we access each file one after the other. Unfortunately the process is not asynchrone, which therefore blocks the rest of the program until it's done.