I think I found the issue. It's related to using a controller, and as you interact with the spawner, if it switches to the controller or mouse/keyboard during the second or two as it opens the spawner UI, it locks the UI. Forcing a Alt+F4 to get out of it.
For context. I use a PS5 controller, and for Railjack, since that mode didn't flow well with a controller a long time ago, I made a profile on DS4Windows using keyboard presses (For one of the menus and an alternate way to force reload since controller reload didn't activate the cooldown for turrets back then, idk if they work correctly now) that activated when I tilt my controller and that generally never affects gameplay. But I guess when it triggers in the menu here, it freezes the UI 99% of the time for me.
I'm probably the only person on Warframe with this issue... 😅 But what I don't understand is how I could always get it to work the first time. But every time on the 2nd interaction I'd freeze the UI. Which is what lead to this post.