Sorry for the double post. I thought about editing my last post but this is a pretty comprehensive (and long) bug report for the current versions of Doom 64 and PSX Doom Consolation Prize so I thought a bump would be more fitting. These were discovered in GZDoom 4.1.3 with Default Compatibility settings.
Starting with Doom 64:
-The Megasphere that spawns in the Doom 64 level "In The Void" can't be picked up. I know I reported this last time but I also checked to see if it happened without gameplay mods and it does. In fact, when I did encounter this and other bugs I went back through the level without gameplay mods to make sure it wasn't a mod doing something it shouldn't be.
https://imgur.com/77eDo4B-In the Absolution level "Forbidden Deeper" there are two arenas where it looks like monsters are spawned and then supposed to be launched into these arenas. However, they instead fall into the outside of the arena, making them impossible to kill unless you use the 'fly' console cheat to fly up and shoot them all or use 'kill monsters' to kill them all. I believe it's also necessary to kill them to exit the arenas you find yourself in.
https://imgur.com/aessp31https://imgur.com/Mqz9tNvhttps://imgur.com/jO73hM7https://imgur.com/Id9ZeyZ-In the Redemption Denied level "Secondary Complex" you have to enter a red door to get a blue key. However, you can't exit out the same red door unless you noclip through it.
https://imgur.com/ojVRyNe-In the Redemption Denied level "The Sanctum" there's a missing sprite/thing that I think is supposed to be a Megasphere.
https://imgur.com/XOLovglhttps://imgur.com/cTjnFKf-In the Outcast level "Traps" the Megasphere that's supposed to spawn at the start once you reach the exit (but not activate the exit switch) doesn't spawn. It's the same bug from before.
For PSX Doom:
-In "Containment Area" there's some missing switch textures for these pillars. I don't recall if the original PSX version had the switch textures or not but I thought I'd bring it up anyway. You can still activate them though.
https://imgur.com/7KoXlTLhttps://imgur.com/ggqzTuBhttps://imgur.com/TDcE9aghttps://imgur.com/ZvLMkcc-In "Threshold of Pain" the switch behind the blue key barrier doesn't work so the walls blocking access to the teleporter can't be reached unless the player uses noclip.
https://imgur.com/zAsnKhn-In "Dead Simple" the walls don't lower after killing the Mancubi and their variants when using monster mods (in my case, Doom RLA Monsters with LegenDoom Lite) but they do when in vanilla. I bring this up because I didn't have these issues with prior similar levels "Phobos Anomaly" and "Tower of Babel" in the TC despite using the aforementioned monster mods. I also didn't encounter this when playing through IWAD's either so I dunno if it's something with PSX Doom or the monster mods I'm using.
-In "The Factory" there's another instance of a switch not working which can leave the player trapped unless they noclip out or reload a previous save.
https://imgur.com/2d3zWu5-The level "Redemption Denied" suffers from the same issues I encountered in "Dead Simple". When using the aforementioned monster mods, killing the Barons and their variants doesn't lower the walls that reveal the Spider Masterminds, leaving the player stuck unless they noclip to the room with the exit portal or use idclev/changemap.
-The level "Onslaught" has a switch that I think is supposed to lower the floor when activated. Instead it raises the floor which will either kill a player with insufficient health or leave them stuck.
https://imgur.com/9kYuICFhttps://imgur.com/uE1dTC2https://imgur.com/IeYRnJBhttps://imgur.com/KF2IIF6And that's it! Let me know if you need me to elaborate further on any of the bugs I encountered or need better/additional screenshots for the bugs I mentioned. In the meantime I'm gonna get me some rest/sleep and then get to work on doing a couple of megaWAD playthroughs with MetaDoom so I can provide feedback on that. :D