macOS/hdiutil hanging

For osx_image: xcode11.3, I tried using hdiutil to create a dmg image 10 times ([1][2][3][4][5], two jobs per build) and six of the jobs failed due to hanging for 10 minutes on the stage Reading GPT Header (Backup GPT Header : 7)…

For the default osx_image I again ran 10 jobs ([6][7][8][9][10], two jobs per build) and this time only one job failed in [7] due to apparently just stopping mid compile and did nothing for 10 minutes while none failed to hdiutil hanging.

Mostly I’d like to know what the possible problem could be with hdiutil and osx_image: xcode11.3, since that’s what I’d prefer to use, but I’m also curious about what happened in [7] with the default osx_image.