This issue did happen to me the other day. Though I got the ship made over to me and it allowed me to get onto the ship. Then after that I sent it back to the owner and I haven't had any problems getting back onto it. Might be a possible work around until the issue gets fixed.
Yep appears I can't enter the one I've piloted for months at the same location I am at. It is actually owned by a faction not me though but I am pilot and on crewlist. Had no trouble til about 5 min ago.
Update: I went to bed came back and now was able to enter the ship.
Edited By: Ku`Bakai Roche on Year 10 Day 135 5:41 ____________
There is your problem right there - the backpack. Could be you used the ship before, and have only recently gotten off it. Within the last several months it has been changed so that items being carried also count against the weight/volume of the ship capacity, not just those on the ground in the room. So, you'll either have to dump the backpack, or get a bigger ship.