Not sure whether this fixes the current "Discovered By" bug. That wasn't rare and it affects planets as well as stelllar bodies. We'll see when the patch is available.
Good news, and (perhaps) bad.
I discovered an unclaimed system with 62 objects (including 2 stars, 2 belts). I Detailed Surface Scanned all the stars planets and moons.
When I returned to sell the data, all these had "Detailed Surface Scan" in the "Data to sell" report, and all gave the "First to discover bonus" and showed the "Discovered by" tag in the Systemn Map. So the bug is fixed.
I don't know whether data which was scanned before the fix and sold after the fix will get the "Discovered By" tag. My guess is no.
The new problem seems to be that the detailed surface scan bonus is not applied to all the scanned objects, even though "Detailed Surface Scan" is shown in the report. For example:
Star A 201cr
Star B 1203cr
A1 360cr metal rich
A2 413cr metal rich
A3 456cr rocky ice
A4 20419cr terraform candidate
A5 13731cr terrestial water world
A6 3126cr metal rich
A7 511cr icy
A8 1785cr class 1 giant
A9 1727cr class 1 giant
A10 914cr giant with ammonia life
A11 1689cr class 1 giant
A12 3279cr metal rich
Some of these look wrong. Star A (class M4) has the value of a non-scanned star, compared to Star B (class L1) which has the expected value for a detailed surface scan.
I think planets A1 A2 A5 A10 are also the unscanned values.
I'll raise another ticket.