My GP sent a lease abstract and the tenant name on it does not match the name on the rent roll

I own a quarter of a 2001 suburban office building in Tempe, about 41,000 square feet, and I have never been inside it. Eight months ago the GP flagged one tenant, 6,200 square feet, as a stable hold, mid-lease, no issues. The abstract they sent last week has a different entity name than the rent roll I got at close. Not a parent company situation, not a DBA I can find anywhere, just a different name. The GP says it's a name change after an acquisition and the lease assignment was handled internally. I asked for the assignment document three weeks ago and I'm still waiting. The tenant is paying, which I suppose is the only reason nobody flagged this earlier. My concern is that if we ever go to sell, the buyer's attorney is going to find the same gap I found and it becomes a negotiating event at the worst possible time. The building is sitting at 81 percent occupied and the loan matures in 19 months, so the timing is already uncomfortable without adding a cloudy lease file on top of it. I don't know if this is a paperwork problem or a real problem, but I can't tell the difference yet because I don't have the document.