We have a problem with that LINQ query. I’ve opened an issue here: New-UDUpload fails when using SQL persistence · Issue #1428 · ironmansoftware/issues · GitHub
Just as a technical note on why this happened: When we implemented SQL support for PSU we had a bunch of existing LINQ queries that also work with our existing LiteDB database. We spent a lot of time tracking down and testing the queries throughout the product to ensure they work in both databases.
This is one that snuck through the cracks.