If a Wildcard is not closed properly, then when you preview or send the message, some of your content may not appear!
For example, you might have a wildcard for a first name that should look like this: %%first_name%%.
If you miss the last percentage symbols (e.g. %%first_name), then the wildcard is opened but never closed.
If you close the wildcard with the correct symbols (%% or ##) then the issue should resolve itself and your content should appear again.
If this doesn't resolve the issue, then you may wish to check the HTML code of all components that have wildcards within your email message, if you are comfortable reading HTML code.
What can happen with wildcards is that they will look fine in the editor, but in the code they will be split up. For example:
<font color=”red”>%</font><font color=”red”>%first_name%%</font>
In the above example, the first % of the wildcard is split in the HTML code because it is wrapped in a separate font tag. If you were looking at the wildcard in the email, it would look perfectly normal.
The above example will also cause the wildcard error message to display.