Found in v25.0.0.24 and checked it was still there in 25.0.0.29 but it's not in 24.0.0.72

Open vMix (if it loads blank, this is even more apparent). Right click on the Externals gear and note Outputs 1–4 are missing their pop out menus. Left click the gear and they load but it takes more and more time depending on how many inputs you have (~1s per 20 inputs). If you change show files, the right click menu remembers the last set of inputs and the left click reloads the inputs.