ZDoom

					else if (!(line->activation & (SPAC_Push|SPAC_MPush)))
						// [RH] activate push doors don't go back down when you
						//		run into them (otherwise opening them would be
						//		a real pain).

[code]
else if (!(line->activation & (SPAC_Push|SPAC_MPush)))
// [RH] activate push doors don't go back down when you
// run into them (otherwise opening them would be
// a real pain).
[/code]

Unfortunately it is not possible at that point to determine the actual trigger so it has to abort.

When the 'monster bumps' flag is used with Door_Generic, it can only be opened once despite being set as a repeatable action. This was found a long time ago on Zandro, but it affects the latest ZDoom.

[quote]
The big door has the following flags: repeatable action, player press use, when monster bumps.

Small door has the following flags: repeatable action, player press use. Note how the large door only operates once despite the repeatable flag.
[/quote]

Test wad: https://zandronum.com/tracker/file_download.php?file_id=638&type=bug