As a report of a similar issue, changing the text to right-aligned causes a similar issue.
This issue seems to have been occur by a change in CL7540157. It also seems to be improved by adding the prepass process included in CL2690181.
Reproduction project when the text is right-aligned:[Link Removed](Play Game and press Q key to recreate the UMG.
The reproduction project is attached below.
(Play Game and press 1 key to recreate the UMG.)
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-137604 in the post.