In my experience with custom leagues, regarding roster maintenance there are two "philosophies" of AI managers / GMs that have always stood out:
- a leaning toward getting rid of more players than they acquire
- 30 is the point of inflection for players' ages where they flip from "desirable" to "un-".
My league's FA list is invariably littered with quality unsigned veterans and the trading block is always full of guys 30 and over.
So if you haven't put an age limit on the players you are seeking, I'm not surprised you are getting inundated with offers.
It is at this deeper level I believe the glitch, if any, exists. Although OOTP seems to have predicted IRL trends in this regard.