Here are slapd.conf and proxycache.conf as attachments.
I just wanted to feed back before I leave for a few days. I don't see anything critical in your files. You explicitly give the rootdn write permissions, which is useless, but apart from this everything looks fine.
I've tested a simple setup and it works as expected. I used HEAD and re24 code; the latter is nearly identical to 2.4.17. I also tested with TLS.
At this point, I'm a bit clueless. There must be something we're overlooking.
p.