I created a scoreboard name with a period in it (wf.timer).
I did this because i don't want my timer scoreboard to get affected by other command block modules (wf is short for windfreaker, my username).
The problem with this is that any scoreboard name with a period in it seems to cause the entity identifiers (@a, @p, etc.) to bug out.
I don't know what part of this is the bug. Should the identifies not have this problem or should scoreboard names not have periods in it?
Either way this is a bug, and seeing as I saw no repeats, i'm reporting it.
I am posting an image to go along with it, the first line in chat is the result of the command that i have typed. You can also see it should work, because I have displayed my scoreboard value on the sidebar.
Won't fix, per Searge's comment on MC-51960.