We took an island over from another company that placed their claim minutes before we did. Once we despawend their claim and started claiming, they put down another flag on a different part of the island (which doesn't make sense if we were claiming).
After some more pvp and wiping them, our claim finally took hold, but their flag remained on the island. Once their upkeep timer expired with no gold the flag finally despawned.
Since then, our "combat mode" timer has been stuck at 0 during that period, and our settlement claim does not show on the map, even though it still shows us owning the settlement. We also were put on a timer to change the combat period for 2 days.
Everything else seems to work, but the bug of having no combat timer, even though we are in combat, and not displaying our settlement on the map, makes us more prone to griefing and island spawning.
