Have you checked the firewall ports are opened?
I have seen such behaviour when the nodes cannot communicate with each other.

As you haven't mentioned which verison of SLES you are using - I assume SLES 15.
It's using firewalld by default and that doesn't have a firewall service by default.

On my test openSUSE 15.1 I am using the following:

# cat /etc/firewalld/services/high-availability.xml
<?xml version="1.0" encoding="utf-8"?>
  <short>Custom High Availability Service</short>
  <description>This allows you to use the High Availability . Ports are opened for corosync, pacemaker_remote, dlm , hawk and corosync-qnetd.</description>
  <port protocol="tcp" port="7630"/>
  <port protocol="tcp" port="3121"/>
  <port protocol="tcp" port="5403"/>
  <port protocol="udp" port="5404"/>
  <port protocol="udp" port="5405"/>
  <port protocol="tcp" port="9929"/>
  <port protocol="udp" port="9929"/>
  <port protocol="tcp" port="21064"/>