Bummer deal. This happens when shift valves are gummy and won't move. In serious case it may be internal pump seals leaking pressure to close clutches. Repairs are expensive, and the problem is annoying. Some have success with products for transmission Called MPRS3. A transmission service product made to end such problems using cleaners and conditioners. Source: auto-tune-up-and-repair-options.com Hope this helps. gcWhat make of transmission is in the 2017 Canyon/Colorado with the duramax engine?