I investigated the issue and can not find a problem with scrolling in songs longer than 1 hour.
But there is a problem timestamping songs longer than an hour as the timestamp has no hour element. I will fix that in the next update but there will be a limit at 99 minutes. You will not be able to add timestamps after that time as the time format uses only two digits to store minutes.
So if you need longer songs, I strongly suggest you split them up into multiple parts and use autoplay.