The proxy watermark is showing in random frames of exported sequences.

When I export a clip as normal, some frames contain the proxy watermark (seemingly at random). The media is online and it is only ever single frames that are affected. This has been happening since October, so I have to carefully pay attention to the bottom-left corner of every single export to make sure that the proxy watermark isn't showing--which significantly slows down my workflow, especially when I have to tweak the clip and re-export the entire sequence because of one frame. When can we expect to see this solved?