Thank you!
Yeah, I definitely wouldn't recommend going 1v1 with a Beast (though that does raise the question of whether I could scale encounters somehow). If you're up for it, I'd recommend trying again either with more players or have one person playing multiple PCs, just to test the balance. Hopefully that would also solve the problem of getting constantly interrupted, since the Beast would have more than one target to go after.
I'm glad you liked it in spite of that, though!