Minecraft 1.14.4
Forge 28.1.76
OptiFine HD U F4
Controllable-1.14.4-0.6.1
PS4 Controller CUH-ZCT2E and XBOX 360 Afterglow USB controller

Whenever I do split-screen, multi-monitor, etc Minecraft (having 2 people play at once, one using m&k with other using controller) in the inventory of the player that uses the controller if an item is picked up from any slot, the controller mouse icon thing locks into place, or if doing multiplayer split-screen it locks onto the side of the controllers player window facing the mouse and keyboard player's window.

Otherwise everything else functions perfectly, even while doing splitscreen.

Have you turned on Virtual Mouse for both instances?

I have virtual mouse on the modded Minecraft session and vanilla Minecraft on the other on the same pc. Do both need to use the mod, even though one uses Mouse and keyboard?

I have just tried using controllable for both instances of Minecraft, with no luck. The same thing happens on the controller player's screen with Virtual Mouse enabled on both the controller player's and mouse and keyboard player's screen.

Here is a video of the issue, if it helps.
https://drive.google.com/file/d/19KzJZjX9DzTY-ukI4Dcl6LKRg7NNaUoI/view?usp=sharing

Is this a problem on the lastest version? I patched some issues related to Optifine and I noticed the video you sent you are using Optifine.

Is this a problem on the lastest version? I patched some issues related to Optifine and I noticed the video you sent you are using Optifine.

Hi there.

This was nearly 2 years ago, so I have long since uninstalled it. I'll try it again and tell you if it is still the same (either tomorrow or the day after). Thanks

Just checking in to see if you have an update @megabytesme. All good if you haven't got around to it yet.