After several Routing, placing fraction to fraction of a circuit into a board. Routing and Unrouting,  suddenly the Autorouter did not hit 100% routing anymore. Returning to the first circuit fraction as in the begining, which is a very simple circuit,  where 100% was sure, the Autorouter did not hit even 78% and leave 122 undone tracks. Even reducing the track width and almost any clearance. After many and many retries, I decided to start a fresh board and then the Autorouter had worked fast up 100%. Therefore, I solved my problem, but the Autorouter seems to have one issue. My version: 6.4.4 build (august, 15, 2020). I realized that the track constraint was anounced as violeted (at the left panel) but the "design rule" popup shows a clean table; allows me to add others contraints but do not show that one which I issue before the first Routing. I have yet the "strange" board with the issue. I realized that the support team would like to know. Regards. Jorge