I am having great difficulty getting Bridge to properly display preview icons. I have found that Bridge will show the proper Preview Icon for each asset so long as I don't clear Bridge's cache or check the asset out. As soon as I do either of those, bridge uses a blank icon instead of the one provided by IGetPreviewIconHandler. What's more, when I cancel a check out, I find that Bridge continues to display a blank icon even though no changes were made to the asset and its modification date returns to the same value as it was prior to check out.
I can see my IGetPreviewIconHandler get invoked, and I have ensured that an Icon object is returned, but Bridge simply ignores the result. Normally I would suspect an invalid ETag or something, but the IGetPreviewIconHandler does not use ETags to communicate changes (so far as I can tell).
Does anyone have some insight as to what might be happening here?