Null values when appending to PostgreSQL

[BTreeTech]

I am appending features to a PostreSQL table/ Postgis layer.

• If I append using the "Just append all features...." option - all is fine
• If I append using the "if a duplicate is found UPDATE...." option and there is a duplicate - all is fine
• If I append using the "if a duplicate is found UPDATE...." option and there is not a duplicate I get an error when it tries to add the feature. The error is ERROR: null value in column "uuid" of relation "MyLayer" violates not-null constraint - since there is a uuid for each feature I assume something else is happening.