passing URI /path to server when loadbalancing

BIGIP won't strip the URI part by default, unless there is iRule/ltm policy configured to do so.

There is no explicit need of sending the URI part to the server. You would need to investigate who is stripping it. Is it F5 or proxy/server on the path?

May be to start with, you can log in iRule to see if F5 is sending /uat/login to the server. Something like below

when HTTP_REQUEST{
log local0. "client --> F5:  [HTTP::method] https://[HTTP::host][HTTP::uri]"
}
 
when HTTP_REQUEST_SEND {
log local0. "F5 --> server:  [HTTP::method] https://[HTTP::host][HTTP::uri]"
}