I have claimed 50-100 hexes, but not seen any strongbox.
Is this normal?
Am I blind?
Or is it bugged?
Using mod v 1.5.10
(No other mods, just space, elev rails, qualiy and base)

They have a small (1%) chance of spawning in each hex. If you've claimed over 100 hexes so far and haven't seen one, then you're dipping below the luck of the average player. Go figure, right?

If you wish to trigger one to spawn on your next hex claim, go into mod settings and set "Strongbox Spawn Chance" to 1. Then claim a hex, a strongbox will spawn, and you can set the setting back to 0.01 (or whatever you want).