This is one of the examples of combats which (unless some strange mistaken e/a identification) apparently have no correspondent among the possible USAAF units involved.
One (only partial) solution would be to write to
firstfighter@comcast.net and ask for a copy of the DORs (Daily Operation Report) of the 1st FG Squadrons for the mission of that 30 April 1944.
It is strange though that the Luftwaffe on the same day (and possibly same mission of the ANR fighters, as timings and locations seems to coincide) claimed three B-17s and one is probably the B-17 of 99th BG (MACR 4610), lost in the area of the claimed combats and about which one eyewitness, although reporting that it could have been shot down by flak, reported not to have been able to follow its chute because "attacked by enemy fighters"...
Clearly those P-38 claims most probably were unconfirmed ones, but - as an example -I generally beware of reports of lost planes like the one of Maj. Barker whose destiny was not witnessed by anyone and attributed to "mechanical reasons" (it cannot be excluded he was shot down while he was on his own, IMHO).
There are lots of "grey areas" (overclaiming, assuming wrong things, etc) when searching for specific reports and claims, particularly about air combats and this is no exception, unfortunately, as several early ANR combats are concened.