Yep, you nailed it. Scroll down through this sub-forum and you'll see the same problem reported (and solved) a few times. BYOC received a shipment from a supplier that had some 5458 JFETs mixed in with the BJTs they had ordered, and didn't realize it for awhile. And JFETs obviously do not function correctly in this relay switching application. But as you found out, a 3904 (and pretty much any other general purpose NPN BJT) will do the job here.
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