Flags not being reliably recorded for anonymous users

I am having a problem with flags not being recorded when submitted by anonymous users. I am using version 6.x-2.0-beta6, with SessionAPI 6.x-1.4. After reading through documentation pages and the other issues discussing this question, I believe I still need additional help with this process (it is probably something I am missing, rather than a bug, so I have tried to mark this issue as such)

I have created a content type that stores proposals for a local community, and would like community members to vote for those proposals they favor. I wrote a simple view that lists each proposal, along with a "flag this" link and the counter of votes received so far. You can see the list at https://ksacommunity.osu.edu/group/dayton .

When I log in to the site and vote, everything gets recorded successfully. However, when I try to vote anonymously, the flags are not consistently recorded with the counter incrementing. Many of the surrounding behaviors seem correct - the page reloads, the status message reads that the vote has been recorded, and the flag link changes to an unflag link. However, the counter does not increment consistently.

I at first thought that the caching system was the problem - so I added the bit of code from http://drupal.org/node/999102 that reads the page generation time. That timer seems to say that the page is not being served from a cache. Furthermore, when I look at the value for flag_counts.count I see the value not incrementing after I hit the flag link. So that seems to rule out caching.

I have tried using the flag link in the view, and on the node display page. Each seems to work the same way. I built the view using "by any user" in the Flags relationship, as recommended at http://drupal.org/node/999102 (with the exception that I didn't see duplicate results, so didn't seem like I needed the "Distinct" flag recommended - when I enable it, the behavior does not seem to change).

However - and this is where things start to get weird - there are times when the votes -are- recorded. As I am writing this report, I tested anonymous flagging on two computers and three browsers (Chrome, FF, and IE). The first handful of votes (Chrome and FF) did not get recorded although the rest of the behavior seemed correct. When I tested in IE, however, the votes -were- recorded. My next test on the alternate computer in Chrome was also recorded, as was the "remove your vote" link from Firefox on the alternate computer.

I'm hoping that this is enough information to help troubleshoot. I'm a bit mystified at this stage, so I am hoping that someone has seen similar behavior or can point me in a direction of what I've done wrong.

Thanks,
Matt