Interesting. Now you have me doubting that the beacon I found at around 21.5E is Gov Sat. When I first found Govsat on X band in February, it appeared to be a bit west of Skynet at 25.1E, i.e. around 23.5E. However, a month or so later @Feedsat_DXer and I could see tests at 21.5E ish. My dish is too small to get a good fix at X band though but Feedsat's is probably more accurate. Satellites Community - 21.5°E SES-16 (GovSat-1)@s-band reported back in February that GovSat-1 TT&C came from 23.5°E instead of 21.5°E.
Now there is also a recent TLE that has GovSat-1 at 23.5°E.
Now it makes more sense, HYLAS 4 can do its in-orbit testing near 21.5°E (actually, 21.3°E is more accurate so far).
Checking its position against SBIRS and Astra 3B, again, I have convinced myself that that I must have found Hylas 4 (or 5 as it is called in some places). The 20.2005GHz beacon did not move to 23.5E.TLE's originating from the McCants' list have empty "revolutions" fields. Therefore the orbit number for SBIRS and GovSat in your screenshot must have "bogus" values.
Unfortunately, only 2 TLE's were issued so far for GovSat-1: 21.5°E on 25 February, and 23.5°E on 22 April.
Maybe GovSat-1 observations are easily confused with Eutelsat 21B and Astra 3B respectively... who knows.
Anyway, GovSat-1 is operational officially since 19 March: GovSat-1 Satellite Goes Operational