I have assigned the keys 'option' + 'space bar' to open the search bar of Alfred.app, and interestingly, if I have 'Stage Manager' activated, the BetterTouchTool application prevents the Alfred bar from staying open, disappearing as soon as I lift my finger from the space bar. If I do not have Stage Manager activated, the behavior is correct, and even with Stage Manager, if I configure the opening of Alfred5 with another combination, for example, 'control' + space bar, the control is as expected. Why does this behavior occur? I would like to continue using 'option' + 'space bar' for Alfred5 even in Stage Manager mode (and of course, with BTT active). Any suggestions?"
Does the same thing happen with both leftOption+spacebar and rightOpt+spacebar?
I'd recommend using Karibener. It's an extremely lightweight key remapper. If one of the option keys works correclty, then just remap left option to send a right option keypress. If neither work, then remap the option --> control, and then in alfred set your shortcut to control+spacebar.
You can go more in depth than the picture below (for example, limit the remapping of the key to only when used in conjunction with spacebar) if needed, so that other shortcuts aren't affected. Good luck!