There is not s duration limiter. Since Avid went to MXF, a clip can be hours long with no issue.
Avid links material based on source name and timecode.
The first thing I would do is open a new project, and link just 1 clip using AMA or as few as possible using AMA, then see if it works.
I anticipate your camera probably named each clip the same thing (Some P2 cameras do this). 001.mxf, 002.mxf, then when you change cards it starts again at 001.mxf.
Some of the benefit/detriment of working with FCP or Premier is that they allow you to mask problems. You can import a clip from multiple locations and it will keep them separate (until something becomes unlinked, then it is a disaster). Avid requires you get this straight up front, otherwise your clips could become a jumble, mashup of each other. This would be like shooting a film, and having the same keycode on each frame.
The proper workflow would be to rename your P2 files something unique (using a P2 utility, not sure if you are mac or pc). Then AMA link them in and start working. Eventually you should consolidate your clips by selecting in your bin, right clicking and consolidate.
Remember in FCP where, everything worked better if you imported and rendered everything in prores? You need to consolidate your material, which gathers it into a specific location where Avid can always find it. It does not convert you material, but it tracks it better.
James Beattie
ACSR Elite/Avid ACI, Apple Certified Technician
Consulting for Workflow and Digital Technologies at Comprehensive Technical Group