"Failed storing DocumentUri to ProjectWise"
This could be related to the Integration Server name and/or the ProjectWise datasource name has changed, which is currently not supported in this release of Transmittals.
From the BTSImplementation guide:
Renaming the ProjectWise datasource after configuring Bentley Transmittal Services is
not recommended, as it can break certain Bentley Transmittal Services functionality.
If possible, change the name back