Im having problems with haproxy (v1.5.18) but i believe the problem can be a configuration, i will explain my setup:
The request is made by php with curl.
CLIENT >> HA-SITE >> WEBSERVER1 >> HA-WEBSERVICE >> WEBSERVER2 [EMPTY]
The problem happens when WEBSERVER1 tries to get statitics from HA-WEBSERVICE
(returns empty).
But if i connect directly WEBSERVER1 to WEBSERVER2 the problem does not happen.
CLIENT >> HA-SITE >> WEBSERVER1 >> WEBSERVER2 [OK]