Hello,
First I would like to say that I really like MusicBee. It's by far the best Music manager and player I ever came across and I use it for quit some years now.
I believe that since version 3.3.6904 or 3.3.6962 there's something not correct with the library statistics for "most played artist". This is the case if you have more than one artist in the Multiple Artist Splitter. If you have two artist in the Multiple Artist Splitter than the second artist will counted twice, the first artist will not be counted. If you have 3 artists in the Multiple Artist Splitter than the third artist will be counted 3 times, the first two will not be counted.
For example, the first track from the Album Nashville Skyline from Bob Dylan is Girl From The North Country which is a duet with Johnny Cash. I have in the Multiple Artist Splitter Bob Dylan as first artist and Johnny Cash as second artists. It's displayed as Bob Dylan with Johnny Cash. In this case Johny Cash is counted twice for each time the song is played and Bob Dylan not. If I reverse it and make Bob Dylan the second artist than Bob Dylan is counted twice for each time the song is played and Johnny Cash will not be counted.