Slain monsters of the deep that failed to show the collect reward button... in this case 3 of them! Shipwrecks too... two this time. Bug? Sorry if already discussed... did have a quick look but couldn't find anything. P.S. also notice the imbalance between EP and BP... Please add more ways to earn BP!
Captn Dutchie- this is weird. The only thing I can think of is that sometimes on a long sail, monsters that are re-born along your path show that they have been slain but your ship has already sailed beyond. Once the sail finishes, those re-born monsters or ships pop up in that spot along your path. Those 2 ships in the second picture look like this, to me at least. I have seen it quite a few times. other than that, I have never seen a monster that I definitely destroyed not show the reward. Hope this helps! Cheers and happy sailing!
As @Oak Island said, sometimes it is simply monsters/ships spawning in your path after your voyage started... However there is also a bug... if a monster/ship spawns in exactly the same tile on both maps - it appears to prevent them from being able to be defeated! It may simply be that the one that spawned on whichever map first, must be destroyed first - or it may be that once it has happened they both become indestructible (I'm not certain which - I haven't tested it enough).
Thanks for the responses @Oak Island and @peg-brain bob. I confirmed it is monsters/ships spawning in my path that I have already sailed and they do pop up after I unload my remaining pirates from the ship... I usually do this via my base and not the map, hence never seeing them respawn... haven't come across the other bug yet, but will keep an eye out...