Changing support unit HQ. Bug?

[Baron von Beer]

Sorry if it's been mentioned or explained: When you manually reassign support unit's HQ, the list seems to be limited to 19 slots. If more than 19 HQs are in range to transfer, only the nearest 19 are available to select on the list.

Eg: I select an SU in AGC, and the 19th choice on the list is Luftflotte 4, 16 hexes away. I do the same with AGS, and the 19th is 9th Army, 29 hexes away. Same with the rest, never more than 19 choices, and identical level HQ's having that 19th slot at different distances, so not simply coincidence that 19 fall within range. [;)]

Possibly similar to air units not appearing on the list with manual air missions?