A copied-pasted FormatText node discards edits when compiling the blueprint. The changes are displayed until then but not saved either.
When I delete that node, place a new one and paste in the intended text then I get the following error on compile:
BlueprintEditorCompileResults:Error: Error Internal compiler error inside CreateExecutionSchedule (site 2); please contact the framework team as we need a repro for this bug!
So the compiler error is related to the string-text conversion: after deleting the FormatText node, the converter’s output slot still indicates an existing link: