The plugin fails to be created with the name "Button". The name button or BUTTON works as a plugin name. If there are some names that plugins cannot be called, then an error/warning message in the output log stating that there is a conflict in names would be helpful.
The warnings indicate that the name conflicts with the struct FButtonStyle (full log attached)
d:\epic games\ue_4.16\engine\source\runtime\core\public\Templates/IsPODType.h(23): error C2139: 'FButtonStyle': an undefined class is not allowed as an argument to compiler intrinsic type trait '__is_pod'
This is not a regression - checked back to 4.14.3
Result: The plugin is not successfully created.
:Expected Result:* The plugin is created
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-44160 in the post.