Running 16.2.1 (Will double check) and having the same issue.
I distinctly remember seeing them either on a previous version, or on a different project.
None of the suggested fixes in this thread have helped.
I do notice the following reply in another thread:
viewtopic.php?f=32&t=89829#p498080mikea57 wrote:Rohit Singhal wrote:Can you post your logs please
Hi, Do not know where the logs are if any have been generated?
I have now identified the cause of the symptom but not the actual cause as a specific R15 project using .MP4 footage supplied from an iPhone.
Re-checked some R15 Sony FS5 and BMCCP4K projects and they load and respond correctly.
Upon reflection, the footage for which I remember having access to
scopes was shot on an android, and was natively encoded with h.264
The footage that I'm missing
scopes for was shot on iPhone, with a native encoding of h.265
As of recent versions, it looks like Black Magic is putting a good amount of focus into improving and integrating h265 support, but I do remember having to install some external codecs in order to render the iPhone footage on my timeline (Free from the Microsoft store)
I have a sneaking suspicion that Resolve doesn't fully support editing with H265 source footage at this point.
I'm going to try reencoding the source into h264 via handbrake, and then try playing with that on my timeline and seeing whether things change