Those lines seem to cause it:

Code:
say 08.----'-/'03-/        04':::::::::::::'        04\-09'\-'----.
say  08´'-..-|07^08/           04':::::::::'           09\07,09|-..-'`
say       08/\/\             04':::::'             09/\/\
say       08'--´               04':'               09`--'


They are contained within the { } of a multiline alias. However for some reason (as you can see) the colours aren't "closed" at the end of the lines. Probably my mistake, I closed them in all other aliases. Since the line preceding the first one shown ends in a } that way, mIRC considers the alias as closed, interprets these as new aliases and ignores the real final }. The preceding line is:

Code:
say      08{ \/'15o08;07====-  04:::::::.:::::::  07-====09;15o09'\/ }


I checked a backup of my aliases and it's always been that way, so either up until 6.14 mIRC didn't consider a } as closing a block until it's on its own line, or it no longer recognizes the } as closing the { in the beginning of the line. I haven't found anything about it in versions.txt, I suggest it get added with the correct explanation (and probably also in the help file so future scripters can take this behaviour into account). Anyway, closing the colours fixed the problem.

Instead of searching for the string, I just looked in the Alias menu under "s" and saw "say" listed for times. But it was your reply that gave me this idea, so thanks.