I Download OrmLite Source code to generate my POCO from SQL Server. I’m sure I make it work previously… now no success at all. Try on vs2019 and vs2017 on Windows 10.
The T4 .tt implementations hasn’t been touched in a year, if it’s an invalid state/configuration error you can try removing the references, generated .cs and bin/ obj/ folders and try using them again.
Otherwise it may be due to something in your DB it doesn’t support.