On two occasions, simultaneous configuration of page protection and pending changes has resulted in page protection generating a log entry, but not taking effect. The protection pages in question are:
https://en.wikipedia.org/w/index.php?title=Eurovision_Song_Contest_2019&action=protect (ineffective protection was set at 11:04, 9 March 2019)
https://en.wikipedia.org/w/index.php?title=Googol&action=protect (ineffective protection was set at 08:43, 16 March 2019)
As of the time of this report, the latter ineffective protection is still current.
Possible related cases have been discussed here:
https://en.wikipedia.org/w/index.php?title=Wikipedia:Village_pump_(technical)&oldid=888017750#Should_this_edit_have_happened?