Using incorrect formatting in FText does not cause compilation errors in EnsureMsgf as it does in other functions such as UE_LOG. This causes crashes to sneak through such as a crash on ensure when in a shipping build if using %s for an FName variable.
This happens in 4.17 and was reported in 4.13
To continue and reproduce the crash (A source build is required to edit the necessary files)
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-55681 in the post.