Inability to ban champions

I don't have a vod to link, but I imagine this glitch has happened often enough to other people as well that it will be credible.

In champion select, sometimes (rare but reoccurring) searching a champion's name with the search function does not show the enemy team possessing that champion, when in fact they do (as evidenced by them later picking it). This has occurred to me many times. Today however, something new happened: not only did searching "mor" or "mord" or "morde" not show mordekaiser as a potential ban, but Mordekaiser was not present on the all-champion base screen. So I couldn't ban him, and obviously the enemy team first picked him. Has anyone else experienced this bug? I notice it about every 2-3 months.