I wasn't sure if this was a BLS-2017 Professional or MBD-2017 issue. Both are running the latest version (29.04.03 for BLS, 13.03.01 for MBD). I am running Windows 10.
I've noticed this last year as well with BLS/MBD 2016 as well. When I go to look at bowlers not on a team, I will have a bunch (i would estimate between 100-200) new ",Vacant" bowlers. And when I look in MBD, I see them there as well. I'm not sure how they are getting added. I actually started my league from scratch when I updated from BLS-2016 last year because my database had hundreds of these "blank" bowlers. Even after deleting them in both BLS and MBD, they still kept appearing.
_https://www.dropbox.com/s/1ljh5szvwsjg0wy/Photo%20Oct%2020%2C%209%2014%2001%20AM.png?dl=0 (BLS Screenshot)
_https://www.dropbox.com/s/bocbnbxsqsl5gac/Photo%20Oct%2020%2C%209%2014%2032%20AM.png?dl=0 (MBD Screenshot)