Hi there,
I was working in a 4k terrain, and after bumping it up to 8k, the Mountain Erosion begun to show a weird behavior, where it occasionally stops processing other tiles. There are no simulation nodes prior to this Mountain Erosion node, only height sums/blends, so I assume it's really a new issue.
After restarting Instant Terra, it all went back to normal, but as you can see in the captured video, the bug exists:
https://youtu.be/96zwpaecd9QI couldn't reproduce the issue, but I'm sending an e-mail with the project attached to it, just in case.