I've converted a project from RH 2019 Classic to RH 2019 Update 6 and found a possible bug where any topics in the TOC that point to a bookmark within a page show up as missing...
The properties appear okay:
If I re-add them using the New Page context menu, the red X appears and the links appears broken after a short while.
I can't open the page from the TOC, and I get red error messages saying that RH needs to be closed.
When I publish, the TOC does appear to work okay in a responsive layout.
The problem didn't exist in RH 2017 or 2019 Classic.
I think there is a bug here. I just added a bookmark to a topic in a simple new project. On adding a link to it from the TOC, I got the error message telling me to restart RoboHelp.
Like you, it works OK in a responsive output. I will report it.
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