I have this same behaviour in my dual-boot IBM Thinkpad T430 i3 running Mint 19 and Mint 19.1. A few days ago I upgraded to Mint 19.1. All seemed to be running flawlessly, no work lost during the upgrade, though the scroll problem persisted. Then today after switching back from Win 10 - which on the same laptop does not have that scrolling annoyance - I noticed BOINC seemed frozen with no jobs listed and saying it could not connect. I spent hours reloading BOINC and trying various fixes (though I have to admit I dont know much about Linux).
Anyhow using Timeshift to go back to Mint 19.0 worked, though I lost the jobs that were in progress.
Just adding my 2c worth... I think Mint 19.1 or BOINC might have a few bugs at this early stage of adoption. I went back to using Version 7.9.3 which I got via the Mint Software Manager. Not sure what version was running when I was using Mint 19.1.

I am a fan of Mint, and I have installed both versions, but not at the same time.
What I meant to say was I have a dual boot Win10 - Mint set up, and ran both Mint 19 and 19.1 today, but not at the same time, and when running these on the same computer, they both exhibit the scrolling problem mentioned by the OP. I uninstalled 19.1 and used Timeshift to backtrack to 19 to get BOINC running, because BOINC froze on Mint 19.1 and re-installing BOINC did not help. But now everything is back to normal.