Merge Duplicate by ID
For the past few weeks I've been trying to merge my living father's two duplicate records (LNX8-R3S and LXK2-TD4) into this correct record (GF37-SDR) but I continue to get an error message that says: "There was an error reading data from the server. Please try again later." And, as stated, this has been happening for a few weeks (through Google Chrome).
I also tried this through Microsoft Edge, Google Incognito, and my wife's pc, with the same result. I tried on my mobile, but I don't get the Merge Duplicate by ID option where the Help says I should (under the three dots top right on the Details page).
Please help so I can get my 85 year-old father started for the first time in his life now that he's expressed interest.