I always route with Online DRC on so that I can realise when I've done a mistake, although this suddenly stopped working during my last PCB design and its been very frustrating to have to perform a full design rule check for every slight change. If I move two components onto each other, or even place a via to short two tracks, Altium does not show any violation (the green 'x' marks) until I perform an actual Design Rule Check and then they show up, so I don't think its an issue of visibility. It also seems to be affecting other parts of the software as if I try to implement teardrops and I make sure to uncheck 'Force teardrops', I still get teardrops being placed and causing violations.
It seems that the issue is only present for my current PCB as it is working when I load up previous designs.
I have tried to turn it off, restart Altium, turn it back on, and restart Altium again but with no success. I have also tried to reset Altium's preferences but to no success either.
Is there anything else I can try?