I don't think that you should fix this, because only a dozen or so of us use the meta forum, but you should know that the previews you get here are also not always right. I don't have time to type a comprehensive list, but a simple example is the following:

Set "Format comments as text." Type SSa=bSS, except with the capital S's replaced by dollar signs. I have done this below

<latex>a=b</latex>

In the preview, they are displayed as dollarsigns (as I would expect, since markdown is turned off.) But, when you save changes, the first double dollar sign is changed to "<latex>" and the second to "</latex>". Moreover, this is not just a display problem; if you go back and edit the post, the double dollar signs will be changed there too! (To my mind, this is terrible design. Sanitize my input however you want for display and processing, but store my original characters, dammit!)

I have tried using Markdown's code setting as a work-around, but I couldn't find a way to get this to work either. At the moment, I have no idea how to get you to see the string of characters that would be obtained in a normal text editor by hitting "Shift-4, Shift-4, a, =, b, Shift-4, Shift-4".

Given that you don't use it, I'd advise turning it off. I'd be quite interesting in knowing why it didn't work, but that's probably an email discussion than a forum discussion.

testing, testing, $$a=b$$