Further test show that the issue is a conflict between the 50m auto-detection circle and the radial menu reload function.
When playing as an SPG, when your targeting cursor is outside (to the left of the auto-detection circle in the image), the radial menu's reload squelch does not function. However, if you are in overhead view mode and move your cursor to the inside of your auto-detection circle, the reload squelch becomes functional again.
While this is a minor issue, more dedicated Arty players that play the support role entirely in squelching targets, reload times, etc., it's a bit of an annoyance to have to move the cursor across the map just to squelch your reload time, then again center on a target before reloading is complete in the vehicle.
Just an FYI.
THX