Please refer to
viewtopic.php?f=21&t=90190 to find out what detail would help in a report - your Resolve version, system hardware, OS version, codec etc.
Under Logs, you can find this hint if you're not able to post URLs:
If you are unable to post a link, put a space in the path so the forum doesn't think its a link, eg. my logsarehere. com
If you feel that screenshots/pictures would help illustrate the difference between observation and expectation, please include some.
Lastly, do look up "Input mismatch" in the DaVinci Resolve manual (from the help menu) - in case the resolutions between your timeline and your clips aren't the same.