https client changing from TLSv1.2 to TLSv1 while loading webpage

Analyzing a capture of an https client talking to a server (A10 load balancer in this case), where the client is experiencing an SSL timeout issue, and the site fails to load. This happens at a random interval, and appears dependent on the current load the A10 is handling.

Looking at the capture, I see the client, for no reason I can find, change from TLSv1.2, and then the next request is for TLSv1. It will pass data with TLSv1 for a few sessions, and then eventually the client tries to connect via SSLv3, and never receives a response from the server (and it's not supposed to). When the client switches to SSLv3 is when the website times out with an SSL error.

What causes the client to change the TLS version while communicating with the same website?

Could previous Secure Session information from the server be telling the client to build future sessions at a lower version?