Let me know if you need more details, but here's the gist.
When I use Bobby with my current few mods, it works just as advertised, but when I add Immersive Portals to the mix, Bobby appears to simply stop working. No crashes or anything, but my "artificially expanded" render distance reverts to the normal server render distance.
I don't use many mods at all, typically just Iris, Lithium, and a Leaf Culling mod. So I feel like my setup is sterile enough to deduce that it's just Bobby and Immersive Portals not playing nice. Not sure how though, and I'm not getting any errors or crashes to see why.

I had the same issue yesterday. When enabled, you can see Immersive Portals just discarding chunks in the multiple dimensions at an interval. A smaller chunk range within the linked dimensions, for performance probably.
I have no idea how these mods work in the background, though I imagine a solution could be for Immersive Portals to let this mod handle just the current dimension, while it still handles the other dimensions it's got linked. Would be great, probably not that simple though.

I also experience this with the new version for Sodium 5.2.0. Is the only solution here to uninstall Immersive Portals?

I should ask: do we know where the source of this problem is? i.e. what mixins are interfering with each other, or something like that. If someone could pin that down, I could try to work on a compatibility patch.

I'm having the same issue. Immersive Portals is installed, and since then, I have the server's default render distance.

I'm not entirely sure what's causing the issue, but I have noticed that the last_access file is just a single null character and all cached region files are completely empty. I'm guessing Bobby just fails to gather the chunk data for some reason.

Unfortunately, uninstalling Immersive Portals isn't an option for me as I'm running a server with a small community and well-established infrastructure at this point. A compatibility patch for 1.19.2 (or any information on how you fixed the issue in newer versions) would be great.

While Immersive portal installed, the fake chunks wouldn't render. Only visible difference was that the cloud distance would expand and the fog too, but no chunks.