Embedded question sometimes has a white background when night requested

I’m struggling to replicate this usefully, so just hoping somebody else has experienced it at some point. One user reporting frequently, I’ve only replicated once. Not been able to view page source yet.

V63.1.6, Windows running as a service. Postgres backend. Latest Java.

It’s a public embed in an EMBED widget in SharePoint (just an IFRAME). Most of the time it appears correctly with a black background. Sometimes, it’s white.

So far, only appears to affect Edge, not Chrome. Not tested in Firefox.

Page refresh normally fixes.

The server is a little under-powered.

We’re connecting via Microsoft App Proxy. Just an authenticated proxy server with a clever way to route traffic to internal servers.

Anyone else experience of this? Any other thoughts?

Looks like I’ve found the problem. I just don’t understand why it ever works!

SharePoint has a way of breaking the url parameters when you edit an existing embed so that

https://myserver/public/question/xxx-yyyy-498b-9938-4345#bordered=false&theme=night

becomes

https://myserver/public/question/xxx-yyyy-498b-9938-4345#bordered=false&theme=night

More clearly:
#bordered=false&**amp;**theme=night

Partial solution is to remove the amp; every time you edit the embed.

Hardier solution is to reverse the order of the parameters so that the theme is set at the start as it’s less noticeable when it breaks.

And another update!

The url sent is always the same whether it’s white or black.

Looks like sometimes it’s mangled by the time it reaches Metabase, other times not.