@scavanger
Ahh yes, I know why…
Its because the match log file that’s downloaded from the Portal, has a folder inside.
Example:
Downloaded File = match_logs_2020-04-27_09_16_34.881.zip
Inside this ZIP file there will be a folder something like = 2020.04.27.09.19.25
What you need to do is just ZIP the 2020.04.27.09.19.25 folder, and then load this new zip file into the replayer!
This will solve the weird, Rounds jumping around issue. 
Hope this helps!
And thanks for the nice message, glad the replayer could be of help. 