No, but I would start by resetting the Crop tool (right click the left-most icon in the Options Bar):
EDIT: I am just on Sierra. Still waiting for the all-clear on the Adobe apps to upgrade to High-Sierra. That said, I haven't seen anyone else mention this specific issue.
Thank you for the suggestions. I tried both tips but neither worked to resolve the issue.
Hmmmm. Assuming it is some weird High Sierra/PS 2018 bug, you can report it here: https://feedback.photoshop.com/photoshop_family?topic-list[settings][type]=problem.
The only other idea I have is to try stamping as a workaround. Select the top layer and use the shortcut Cmd Opt Sh E, which will copy all of the existing layers to one new merged layer. This keeps the layers intact for edits. Does the issue still occur on the underlying layers?
Stamping is my current workaround and there are no issues with the creation of the merged layer or the original layers.
The only issue I have discovered is with the crop tool.
Anyone have other ideas to resolve this? Otherwise I'll submit a bug report.