Today, I can’t Reroll the Very Rare Endeavor [Destroy 18 Dreadnoughts]. And, no, this has nothing to do with the another toon having started the assignment. Because, on my end, I never even started the assignment. Now, I've tried logging out and back in again. Nothing. Zone changes? Nothing. Later, I tried to reroll with another character, no results. It's account wide, so I can see why another character can't reroll, either. So, I decided to at least try and make some headway and do the Endeavor "Destroy 18 Dreadnoughts”. Since, I also had a Rare endeavor in a Hur'q assignment. I went ahead and did the "Home" mission from the Gamma Rep. While I was able to complete the Rare Assignment, I was not credited at all for the destruction of Vedric Hive Dreadnought. So, definitely, something buggy happening. However, if this means I would have to do several TFOs, just to get to destroy 18 Dreadnoughts, well, you can kind of see why I rerolled it in the first place.
Either way, if could've completed the Endeavors, today, I would have a Perk point to spend. Which would've been helpful, since the Endeavor system is a rather long commitment to the project.