You're fine on the misunderstanding, that one was me. Did you check the rest of the list to see if the girl's room is just in a different position? As far as I know, it is a room that was modded into the game and those are more likely to be at the bottom, on the end of the list as it is with the Steam version picture. The last three in the steam version picture are not part of the base game, but all of the ones shown in the other version picture are base game locations and the list is not scrolled to the bottom on that one, suggesting there are more options below the visible ones.
As for the placement inside the room (Ex: Desk), that might be a bug in the plugin to unlock positions. It might be doing the opposite or just not having any effect at all. This is why I said to make sure both are in the same spot in the room. Assuming the plugin is NOT working as intended in some way, that would mean that not all positions will be available in every spot in the room and all spots are available. If it is just not functioning, the problem could be as simple as not being in the right spot to have the same options as in the Steam version or it could be blocking the spots. If the plugin is doing the opposite of its function because of some bug, then it may be locking you out of positions or spots entirely.
Long story short, this is likely a bug, possibly with the unlock plugin, possibly with the repack, but a major one either way. The only solution in this case is to wait until it updates.
When I say to check that you are in the same spot in the room in both cases, I mean the pink arrows. Each of those has a different set of categories, the blue list that is missing some options in the other version picture, and those categories will determine what kind of positions will appear available in the list from the touching/service/penetration menus on the right side of the screen.
As for why you can't do certain things, it's because it was not designed that way. You can only do sitting positions on a chair or bench, which includes the bed apparently and is why there are two arrows on places with bench positions. You can only do positions where she is laying down and you are standing on tables like the one in the middle of the room or the desk. You can only do positions where both are lying down in open areas like the floor or on a bed. You can do standing anywhere except on the desk or chair, though this one should have, admittedly, been slightly more restricted as standing positions on top of the middle table or bed are doable and look odd.