I've seen this posted before, but this is different because permissions have nothing to do with it. There is one page on my site where the AutoNav keeps disappearing. It works for a few times, then disappears. The way to fix it temporarily is edit the page, edit the block, don't do anything to it, save it, approve the page and it works again for a little bit. I've tried clearing the site cache, creating a new page and moving everything over and tried creating a new block on the page and replaced the old one. No matter what it seems to just keep disappearing. The AutoNav is set to show 3rd level links.
Try deleting all the add-ons and themes that you installed and use just the default theme and blocks. If it works, then the problem is with one of your add-ons or themes. Otherwise, there is something wrong with your core installation.
That seems a little extensive for just one auto nav block that doesn't work. Anyway, somehow, it seems to be working fine. This time I cleared site cache, created a new page, moved the elements to the new page except for the auto-nav block, set up a brand new auto-nav block on the new page, saved it, cleared site cache again and it's working.
I've seen this exact symptom. One page with an autonav in the left panel persistently disappears. Editing the autonav block, changing one parameter and saving it again will restore functionality. I can then go back, edit the block again, restore the original settings and it will appear normally again.
The block itself is always there, but the content inside disappears.
All other pages work correctly. Nothing out of the ordinary on this page. A simple content block and a nav block.
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