Maybe this is known behavior, but I noticed that when using the following dataset name in an Excel Feature writer in FME Server, that the expression was not evaluated correctly when using the Data Download or Data Streaming services.
"testfilename_@DateTimeFormat(@DateTimeNow(),%Y%m%d).xlsx"
Interestingly, it works fine in Desktop, and when using the Job Submitter service in Server.
Has anyone else encountered this type of issue?