Repro Rate: 3/3
This is a live issue that has been tested to occur in //UE5/Release-5.1 at CL 23058290.
This is also confirmed to not be a regression since this issue also occurs in //UE5/Release-5.0 at CL 20979098.
Images showing the issue the customer is seeing is also attached.
Actual Result: Landscape Layer Mask is not imported.
Expected Result: This should import the landscape layer mask and automatically paint the landscape according to the mask.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-173254 in the post.