XOP Gate --> Is there a limit to the number of parallel instances coming to t

Yes, that's the expected behavior, the OR-XOR gateway waits for the other incoming flow to be activated. That's why this is not a best practice and instead you need to use a script task before (even if it's an empty script task) to join all the incoming flows and direct a single one to OR-XOR.

This is explained in our documentation forum.appian.com/.../OR_Node:

"When multiple flows enter an OR node, the Gateway node pauses after the first instance token passes through – until all other incoming flows arrive. Work around this issue by placing an empty Script Task node between the incoming flows and the Gateway node. "

Yes, that's the expected behavior, the OR-XOR gateway waits for the other incoming flow to be activated. That's why this is not a best practice and instead you need to use a script task before (even if it's an empty script task) to join all the incoming flows and direct a single one to OR-XOR.

This is explained in our documentation forum.appian.com/.../OR_Node:

"When multiple flows enter an OR node, the Gateway node pauses after the first instance token passes through – until all other incoming flows arrive. Work around this issue by placing an empty Script Task node between the incoming flows and the Gateway node. "