I'm using two "call RadioButtonsX" pocedures to initialize both groups of RadioButtons to "Unchanged" and this, when the screen "Relays" opens.
Unfortunately, only the RadioButtons1 group accepts to set the desired default choice. In the second group, absolutely no choice is selected (all three choices are unselected/blank).
Relays is a Screen? If so then yes, make a Clock Timer Block for the Radio Button settings and call that from Relays Initialize, very last of what ever else is put in Relays Initialize. Set the Clock Timer interval to around 200 millis and disable it on first run.
It's not a bug. The Screen is initializing and that has to take precedence. If we put other tasks in that Block, the initialization and the other tasks may not complete - Think of them as "fighting" for the same memory (not entirely true).
So, by setting the other tasks in a Clock Timer, we give the Screen Initialization time to complete first.
Note, it is always a good idea to set Clock Timers up in the Blocks area - you can see the setting and tweak them without going back and forth to the Designer attributes palette. However, you should un-tick the values in the palette.