Vaal beacons repeatedly not spawning in maps

So the following is happening:

1. 3 maps in a row (T15 6 mod, just a precursor tablet for rushing the beacons) the beacon failed to activate even though all the mobs around it were dead.

2. 9 maps in a row, the beacon is just not spawning in the map (not present in the "extra content" section of the UI on the right)

it seems they've just stopped spawning for me. Feels like I'm just wasting my time.

1 also happens for me but rarely (sometimes there are some inactive/buried monsters near it).

For 2:
- the UI section will be updated after you kill the map boss + checkpoints or smth

Even if you don't see the temple triangle in the UI, the beacon exists