1.10 FontString oddities
 

So I'm levelling this rogue on the contest realm and decided I wanted to use the addon called "SpellDuration" for gouge etc.

When I put it on, it gave an error whenever a debuff was added to the targetted mob, so I looked at the source to find the problem. The problem was that {TooltipObject}TextLeft#:GetText(); returns nil at all times. I tried lots of things, such as changing the tooltip object to GameTooltip, etc. Then I made a macro in-game which does the exact same thing in a /script, and it worked. Even stranger is that in the addon, {TooltipObject}TextRight#:GetText(); returns its normal value.

Is this some kind of halfdone protection against tooltip scanners (which would ruin my guildbank addon among others), or a bug, or did I miss something?