Greyed Out Primitive Options: Bug?

I’ve been modeling this off and on most of the day and when I came to add in a UV sphere I wanted to chop up, all the settings for it were greyed out, it’s doing it with all of the Add Mesh > Primitives options and includes the F6 menu, is it something simple (like me being thick,) or a bug? I’m scratching my head a bit here. Bottom left you can see the greyed out menu :confused:

Weird, after switching on the computer this morning and opening up blender in exactly the same state, the options aren’t greyed out any more, I’m assuming this is a bug now, I’m unsure how I should go about reporting this?

i had the exact same problem a while back and a restart fixed it. i wouldnt worry about it. and besides, if you have no idea what causes it, what can the blender developers do about it?

edit: point being, dont bother reporting unless you can recreate the problem for the devs