Interestingly, even when you use Advanced to correct it, it still shows as backwards in the Manager. Perhaps it's just a new display issue, but earlier entries (pre 6.1.9) in the Manager are showing as 192.168.1.255.
Sounds like the you've gone through a number of versions and in one of them the default broadcast address got erroneously transposed during config upgrade. I remember fixing a related issue in 2014.
Thing is, the default broadcast address is only used when adding a new entry in the WOL manager. It doesn't have any effect on any entries already there. So if you've corrected the default address (under the Advanced button), any new entries added with Add IPv4 Target or Save MAC to WoL Manager should be correct.