User avatars not displaying (desktop site)

For the last week or so, user avatars are not displaying in the majority of discussions on the desktop site. It doesn't appear to affect the mobile site (although I'm not a heavy user of it, so can't say for sure).

This appears to be a discussion-specific issue: for the "working" discussions, the avatars will always be displayed correctly for all users on all pages. For "broken" ones, no avatars will be displayed for any users. Whether a discussion is broken or working is not affected by the category it's in or the user that started the discussion

• A working discussion (for me at least): https://www.boards.ie/discussion/2058297298/summer-2023-general-discussion/p1
• A broken discussion: https://www.boards.ie/discussion/2058307753/unseasonable-weather-with-warnings-fri-4th-sat-5th-aug-2023/p1

Unfortunately, the vast majority of discussions are in the broken state. It's almost certainly a back-end issue - the avatars aren't being included in the generated HTML at all.

Broken discussion:

<div class="userinfo-row">
    <div class="userinfo-username">
        <span class="offline"></span>
        <a href="https://www.boards.ie/profile/Niall145" title="View the profile page for Niall145" style="text-decoration: none;">
            <span class="boards-button-utils-as-text js-userCard js-userCardInitialized usertitle-28064212" data-dropdown="user728658-menu">Niall145</span>
        </a>
        <div class="user-tools dropdown-menu" id="user728658-menu" style="display: none;">
        </div>
    </div>
    <span class="MItem RoleTitle">Registered Users</span>
    <span class="MItem PostCount">Posts: <b>137</b></span>
</div>

Working discussion:

<div class="userinfo-row">
    <div class="userinfo-username">
        <span class="offline"></span>
        <a href="https://www.boards.ie/profile/Niall145" title="View the profile page for Niall145" style="text-decoration: none;">
            <span class="boards-button-utils-as-text js-userCard js-userCardInitialized usertitle-28064212" data-dropdown="user728658-menu">Niall145</span>
        </a>
        <div class="user-tools dropdown-menu" id="user728658-menu" style="display: none;">
        </div>
    </div>
    <span class="MItem RoleTitle">Registered Users</span>
    <span class="MItem PostCount">Posts: <b>137</b></span>
    <a title="Niall145" href="https://www.boards.ie/profile/Niall145" aria-label="User: &quot;Niall145&quot;" data-userid="728658" class="ProfilePhotoLarge PhotoWrap js-userCard js-userCardInitialized" aria-controls="popupTrigger-0-content" aria-expanded="false" aria-haspopup="false" role="button"><img src="https://w8.vanillicon.com/v2/841de6882bb01b335b02fac59a938dfa.svg" alt="Niall145" class="ProfilePhoto ProfilePhotoMedium" data-fallback="avatar" loading="lazy"></a>
</div>

Note the second-last line (<a title="Niall145"...) in the working version is not present in the broken version.

@Boards.ie: Mike, can you raise this with Vanilla?