OK, I created several different custom leagues to test this a little further. It does appear that with a negative creation modifier for stealing ability it ends up with negative values that end up "wrapping around" to 255. It also appears to affect the running instincts, though the max value for that stat seems to be 100 anyway. Here are the results of my tests.
Code:
Steal Modifier # STA > 200 # 200 > STA >= 100 # RUN = 100
-25 111 0 111
-10 26 0 36
-5 1 0 10
0 0 1 9
+5 0 8 13
+10 0 14 27
+25 0 35 42
The more negative the creation modifier is the more guys there are with 200+ abilities in stealing and 100 in running instinct. All players that had a STA of greater than 200 also had 100 for RUN. There were people with 100 RUN and not 200+ STA though. I assume those people are the ones that "should" have had 100 there.
Using a positive creation modifier I got guys with greater than 100 in STA but none over 160; none over 106 until I used the +25 modifier.
Hopefully this give enough information for this problem to be fixed. I would think it is an easy fix. I understand the OOTP7 is kind of the priority now, but when the next patch for v6 does come I'd really like to see this fix in there.