Currently on Nintendo Switch myself in v1.17.11 and I have this same issue every time an invitation is sent to me. The notification pops up very briefly, about 2 seconds as mentioned, and there is nowhere I have found to access invitations after the pop up fades away. It happens every single time, without fail so I don’t understand how this issue was flagged as unable to replicate. Same issue across two Switch consoles, with separate Minecraft and Xbox accounts on each, in the same game version.
Player B can interact with some things in the world in a limited capacity. Buttons and levers activate with a sound, but do not initiate redstone signals. Villagers can have a trade window opened, but cannot be traded with even given the appropriate items for the trade. Entities cannot be “pushed” by the player including mobs/villagers and minecarts. Mining still seems possible in all instances of this happening. (Edit: chests can be opened while “locked” and villagers can be traded with but exp** for the villager does not increase. I misunderstood how it had been communicated to me while we were testing)
The “locked” player is the player who has been on the realm the least. This effect transfers from one player to the other when the “locked” player logs off and rejoins the Realm. It transfers again when the newly “unlocked” player leaves and rejoins without the other player leaving.
The “locked” player is usually the Realm owner when we notice the issue is occurring. Today we encountered this again, and the issue was identical.
We have not encountered this issue in multiplayer games off of realms, but we also do not spend significant time doing things in a testing world far apart from each other - and even then the Simulation and Render distances are different than on Realms so there are too many variables for me to confirm similarities off of realms.
Unfortunately neither of us have a PC to render any video. Given that a video recorded demonstration of the issue would need a side by side view of two different players views, I apologize that this is beyond our technical ability to provide.
I am aware of the simulation and render distance limitations of Realms, and believe I was using the terms correctly. Your statement that once the “unlocked” player approaches within Render Distance of the “locked” player, simulation resumes - but it does not resume in the next chunk farther away from the “unlocked” player from the “locked” player’s perspective. This was tested with various passive mobs being in visual range of the “locked” player in another chunk away from the “unlocked” player still being frozen as though they are rendered from the “locked” players perspective but not simulating. This issue occurred again today, and we were both doing different activities than when it has previously manifested. The locked player in this case was near our base while the other was quite distant clearing a desert. Repeating the distance tests once noticed yielded identical results to simulation activation. We were not able to test if chunks that would be out of simulation distance between our independent locations were simulating, given that 4+4-15 should leave 7 chunks where we wouldn’t have any way of observing for simulation status.