I don't know if it is the same problem that the original poster is having, but one problem I've noticed happening since about three or four weeks ago is that the FindaGrave results page no longer opens in a new tab in the top browser window that you are viewing (the one that contains the tab for the originating window), like it used to consistently do.
Instead, if you have multiple browser windows open, it seems to open a new tab in a random non-active window, NEVER in the front window. It does not activate the window that it puts the new tab in, simply leaving it at the same place in the stacking order. So you have to go digging for it. For example, just now I clicked on one of the buttons to open the FindaGrave window, and it opened as the 3rd of 11 tabs on a window that formerly had 10 tabs, that window being the 10th from the bottom of my 17 open browser windows.
For quite some time, I simply thought that the result windows were not opening at all, so I would manually go do a FindaGrave search, using the Ancestry results only as a clue to what name the grave was indexed under. But eventually I went back to some of my underneath windows to finish up the work in them, and discovered the results of several days worth of "presumed failed" FindaGrave links sitting in them.