When a blueprint macro library is opened, an unrecognized tab of compiler results would open with it.
Below is the warning message:
LogTabManager: Warning: Cannot spawn tab because no spawner is registered for 'CompilerResults' LogSlate: Warning: The tab "CompilerResults" attempted to spawn but failed for some reason. An "unrecognized tab" will be returned instead.
Result - An unrecognized tab of Compiler Results would open
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-82665 in the post.