I met a stange problem that TC didn't allocat build in queue to idle machines. We have nearly 100 agents and all are registed and connected. However, nearly 2/3 of them cannot be allocated builds or they are really slow to get build to run (after waiting for several hours). The builds in queue have no dependencies and displayed as "delayed". Therefore, I want to ask how and when TC decides to allocate build to agent? Is there any possible reason to block the build queue? It's too busy or something? My server version is 8.1.1.