I am using version 3.5.8296 on windows 10 machine
I found out that if I group items of a playlist musicbee will count the group header as a song which will miss up the playlist items count.
(https://i.imgur.com/SaX0OJl.pngl)
as you can see the item count start with 2 instead of 1 as musicbee count "circle the drain" as a song. and the same thing for item 5 that should be 3 instead. :)
as the playlist item count increase and the number of groups increase, the discrepancy of the playlist items count will also increase.