Hello gentlemen, The bug for opening .osm models that have used the Calibration measures seems to happen whenever a model is not on the computer or file location where the utility data was entered.
The last message I received was to delete all utility billing information and then try running PAT again. This did work but was not a fix. The model cannot be shared and worked on in PAT without taking out the utility bills. Please let me know if you have an intermediate release with this bug fixed.

"I am looking into this to fix it in 1.9.0. I think the bug is related to the Utility Bill object. In the meantime, can you try removing the Utility Bills from your OSM and then create a new PAT project with that OSM?"