I have a number of people that have new information on FSFT and I am working through the FamilySearch Center list to compare them and update as desired.
Normally it is on the "Share data" tab as I compare and import some facts. After I have done as much of that as I want, I switch to the "Sources" tab.
As you can see in the screen clip below, it thinks there is 1 (one) source that I could consider.
Normally, both sides of the comparison would say "Loading..." as it gathered and sorted the information from both sides to show me.
But in this instance, it did not say loading and never presented that one source for me to consider.
This is NOT a one time event, has happened dozens of times during the import of data from roughly 2500 people (so far).
I went back to Share Data, edited the RM person and saved, then back to Share Data. Now it says there are no Sources to check. But if I click on Sources anyway it says Loading.... and never finds anything --- which seems to make sense except what happened to the Source it thought was there before?
So I ignore for now the fact that I might have missed something (I could add him to a QuickGroup and check again later) and I move on to the next person in the list. The Share data comparison of facts all seems to work OK. It says there are 27 sources for me to consider. I click on "Sources(27)" and it says Loading... on both panels. But 10 minutes later, nothing has appeared. The screen is not frozen, I can go back and forth, but the Sources never appear.
The only way I have found to recover is to close the FS Person Tools, close FS Center, and then re-open it and continue.