That is good to know, some of these types of issues are related to the Os your using. I don't use OSX, but someone else who does may have the answer, or there may be a bug report available. I'll go take a look, and you may want to look too as 2 sets of eyes are always better than 1
The bug database can be found here -
https://quality.livecode.com/
*Edit - I found 91 entries for dictionary issues, but none seemed to match yours. Hopefully someone on a Mac can say, but if not, you might want to report it. I'd give it a few days though.