The {module} tags are not being converted

The Modules Anywhere plugin is not published

Check if the Modules Anywhere plugin is published. Go to Extensions >> Plugin manager and search for the system plugin System - Regular Labs - Modules Anywhere. Then publish it.

There is markup on the {module} tags

If you have copy/pasted code directly into your editor, you might also have copied along hidden HTML tags. So this will also cause the {module} tags to break:

{<span>module</span> ...}

Remove the extra styling or other html tags around and in the {module} tags that might cause problems.

The module does not work

Javascripts and/or Stylesheets are not placed

If you are placing the module via a Custom HTML module, switch on the 'Prepare Content' option in that module.

Some slideshow modules or other fancy modules will not work properly when placed through Modules Anywhere.

Some javascript based modules don't like to be placed any other way than through a module position. Which is quite understandable, frankly.
Modules Anywhere outputs the modules in areas where they shouldn't really be (they are not designed with that in mind at least).

So modules that rely on javascripts might not work, because they can't place the scripts in the right way or something.

The same issue might arise for some modules that place stylesheets (css).

The workaround is to place the module in a hidden module position.
Make a new module position in your template called 'hidden' (or something else if you want), and wrap it in a hidden div.
To do that, add this to the bottom of your templates index.php (above the </body> and debug module tag):

<div style="display:none;"><jdoc:include type="modules" name="hidden" /></div>

And then assign the module to your new hidden module position.

Module cannot be placed multiple times

Some modules (also javascript based ones) don't like to be placed more than once. These won't work either if you place them twice on one page using normal module positions.

In this case, try to not have the module in the side or somewhere else if you want it in the article.

The {div} tags are showing

Since version 7.0.0 the support for the {div} tags have been removed.

There is a message you should see when updating from an older version that says:

Modules Anywhere no longer supports the {div} tags.
If you are using these, you will need to replace them with normal html <div> tags.

If you still need this functionality, you will need to downgrade to Modules Anywhere v6.0.6.

The removal of the {div} support is also stated in the changelog.

The module's output is messed up

Modules Anywhere will - by default - try to fix issues in the html output of the module (including the surrounding html tags).

It does this to prevent html stucture issues potentially caused by the html of the module being placed inside whatever html the {module} tag is placed in.
For instance, if the {module} tag is inside a paragraph (<p> tag) and the module outputs a <div> structure, you get a <div> tag inside a <p> tag.
That is invalid html and Modules Anywhere will fix that. In this case by removing the surrounding <p> tags.

There are however some modules that output invalid html structures out-of-the-box and rely on that faulty stucture to function. When Modules Anywhere 'fixes' that html, the module will stop working.

For these edge cases you want Modules Anywhere to leave the html alone and simply output it.
You can do this by either switching off the Fix HTML option in the Modules Anywhere system plugin settings, or by switching this off via the {module} tag:

{module name="Name of the Module" fixhtml="false"}

The core "Module" editor button gets disabled upon installation

Correct. Joomla has its own Module editor button. Seeing Modules Anywhere has similar - but much better - functionality, Modules Anywhere will disable the Joomla core editor button plugin upon installation / update.

If you want Modules Anywhere to leave the Joomla core editor button plugin alone, just add modulesanywhere_ignore anywhere in the custom_data field of the core Module editor button plugin in the database.
This requires you to do this manually in the database. You can find the Joomla core Module editor button in the #__extensions table.The row you want to edit will have plg_editors-xtd_module in the name column.