Alva not spawning in map (rare frequency)

I alch and go running Kalguur and Alva in Jungle Valley and Mesa:
Kalguur Map Craft
1x Monstrous Lineage
4x Divination Scarab of Plenty

I now have over 50 itemized temples. However, I noticed that sometimes Alva does not spawn at all. Over these 50 itemized temples (not 50 completions of alva btw, using scarab of timelines also), there were 2 instances of alva not spawning in the map.

Kalguur ores are there, the mobs from scarab of plenty are there, but there's just 0 Alva, map is 100% cleared. Temple is also claimed from alva before running a new map to start the fresh 12 temples. Triple checked atlas and it says 'Your maps contain Alva'. Not game breaking but very odd

Same

Interesting. How many times did it happen to you? I made almost a full stash tab of temples with Locus and/or Dory (and more than another tab of "rejects") and it didn't happen to me once.