FM 13 hangs on switching layouts

[Cable]

So here's a weird one. I'm wondering if anyone else has seen it.

Overview: I have a database for tracking plant inventory for a wholesale plant nursery. The size of the pots is measured as a gallon size and abbreviated in the system. So a 1 gallon pot is a G1, a 2 gallon pot is a G2, a 3 gallon is a G3, etc.

I have two layouts for viewing the data in either a list or as a form to show more information. Pretty standard stuff. When you click on a magnifying glass icon a script runs to see if you're on a iPad or iPhone. If you are, it sends you to a layout optimized for mobile devices. Otherwise it sends you to a layout that has existed for about 10 years.

In FileMaker 12 it works perfectly. In FileMaker 14 it works perfectly. In FileMaker 13 it works for everything except a G2. For the G2s it hangs and just spins and spins and never goes to the detail record. I always have to force close FM. At first I thought something had happened and all of the G2s somehow got corrupt. But, if I change the size for that record to, say, a G3, it works just fine. Change it back to a G2 and it hangs again. But again, only for FM13 (both Pro and Advanced).

Since I plan to switch everyone over to 14 in a month or so I suppose it doesn't really matter, but it is bugging me why this could be happening. Anyone ever see something like that before?