Shared matches confusion

[ElizabethHerts]

I am doing Version 2 of my colour matches as I found my first attempt wasn't very successful.

First I did colour matches for RD with whom I have a very strong match. He is descended from my grandmother's sister.

Now I have started with the first person he matches with. I entered the names on my spreadsheet, now I am entering details such as the number of cM shared etc. However, when I returned to this second person WE the names he matches to have changed - some have disappeared and there are extra names I didn't have before.

So just how accurate is this? And why the different results half an hour later?
It doesn't fill me with confidence.