When I was just viewing the MathOverflow Improving Cauchy estimates?, this is what I see for the question & answer members' "flair" sections:
Doing a refresh causes the reputations to briefly appear, but then disappear. The page source for Guido's "flair" section is:
<div class="-flair">
<span class="reputation-score" title="reputation score " dir="ltr">377</span><span title="6 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">6</span></span><span class="v-visible-sr">6 bronze badges</span>
</div>
The 377 is this member's reputation, so it's included in the HTML text. For comparison, here is the HTML text for the OP's "flair" section of Are there four numbers in AP such that their prime factors are also in AP? where the reputation is shown:
<div class="-flair">
<span class="reputation-score" title="reputation score 14,361" dir="ltr">14.4k</span><span title="4 gold badges" aria-hidden="true"><span class="badge1"></span><span class="badgecount">4</span></span><span class="v-visible-sr">4 gold badges</span><span title="25 silver badges" aria-hidden="true"><span class="badge2"></span><span class="badgecount">25</span></span><span class="v-visible-sr">25 silver badges</span><span title="70 bronze badges" aria-hidden="true"><span class="badge3"></span><span class="badgecount">70</span></span><span class="v-visible-sr">70 bronze badges</span>
</div>
I don't see anything specifically different which might explain why the reputations are not showing on the MathOverflow posts, so I suspect the problem is likely occurring somewhere else.
Note this problem is not occurring to me for posts on this site or on the Mathematics site, so I'm not sure what other sites, if any, this problem is occurring on.
display: nonestyle to the relevant parts. $\endgroup$