I have a streaming case, where i stream from 2 sources: source1 and source2. I write to seperate streams to pick the data up from the landing area (step1). then i write 2 extra streams to apply some tranformations in order to give them the same schema and have the 2 streams write them to the same target (let's call it union_stream) (step 2). So far everything works fine. Then i write another stream to apply some tranformations to union_stream and write it to union_stream2 (step 3).  In this step all the data from source 1 flows perfectly through the stream but the data from source 2 doesn't. When i filter on source_name = source2, i get the error: Keeping the source of the MERGE statement materialized has failed repeatedly. Even when i execute step 3 without streaming i get the same error. I have also tried to not perform any transformations in step 3 and just do a MERGE into a table with the exact same schema, this led to the same error.

Any help would be appreciated. Thx in advance