The modulation amount tooltip sometimes stays displayed instead of timing out. Here's how to reproduce this:
Open Surge. Enable routing mode. Apply modulation to something like Filter Cutoff.
Double-click on the mod amount slider (blue slider), then exit out of routing mode using the mouse (Mouse3, Mouse4, or Mouse5) before the mod amount tooltip disappears. Exiting with Tab won't trigger this bug.
See the bug. The tooltip will stay on screen until tweaking another control or changing selected mod source in the routing bar.
The modulation amount tooltip sometimes stays displayed instead of timing out. Here's how to reproduce this: