We did a merge from IPBv3, and almost all of the post content (and signatures) is not rendering all the bbcode. Things like b, url, quote. Thing is, SOME posts and signatures are ok! So we know its working... but most are not for some odd reason (talking hundreds of thousands).
Is there a "Rebuild" option somewhere we are missing? Something that will go through and click 'edit' and 'save' on every piece of content so we don't have to do that manually?
It could be a setting, of the subforum the post is located in. Forum settings, see if "allow mycode in posts" is enabled or not for the specific subforum(s) where the problem appears. In that case the posts that work, vs. posts that don't work, would also be located in different subforums and the problem might migrate if you move the thread to the non-working subforum. Not sure if there are similar settings elsewhere.
If it's a bbcode that mybb doesn't understand at all (slight differences between forum systems), you can usually work around it by defining custom mycodes for them.
This happens in the same forum, subforums, same users or not. Also, the super admin post's should not be denied anything as well, and it happens there hit or miss. All one has to do is hit 'edit' and 'save' on the post, and it correctly formats most of it ... same with signatures.
However doing some 'before' and 'after' looks at the database I think I see the issue.
Old bbcode for url is to include double-quotes on the url part, so [url="someurl"] ... whereas after hitting 'save' in MyBB, it saves it as [url=someurl].
Also for quotes (quoting a prior post in the thread), the old bbcode was like [quote name='Persons Name' timestamp='1598552941' post='453721'] ... but after hitting 'save', it just turns all of that into a plain [quote] and shows up as a quoted box of text. If I do a new quote/reply, the MyBB code is of [quote="Persons Name" pid='453721' dateline='1598552941'] ......
I was looking into the merge system's bbcode_parser.php and it has some bbcode reformats, but none of the ones that are causing issues. I will add proper conversions in and try a whole conversion again.