Something went wrong...as a DM

Hey, I’m having an issue with one of my campaigns.

I wanted to split a boss fight across two different maps. On the first map, I had already rolled initiative and started the encounter. I then opened the second map to set up and start initiative there as well. This all happened before any of the players had joined the maps. Ever since then, I’ve been getting the error message "Something went wrong" whenever I try to access/start the affected map as the DM. What’s strange is that only I, as the DM, am affected. All of my players can still access and see the map without any problems.

When I started initiative, I had selected/marked everything on the map, including hidden tokens. Could this potentially be causing the issue? I’ve also tested other campaigns, and I can launch those without any problems, so the issue seems to be specific to this campaign/map. The problem has been occurring since yesterday, and I would really appreciate any help troubleshooting or fixing it, as I need the campaign for an upcoming session.

Thank you!

Similar situation here.  About 11 hours ago, I was running a combat encounter on a custom map for the party and mid-way, the browser reloaded, I briefly saw a 'No Map Selected!' message, which turned into a 'Something Went Wrong!' message after about a second.  When No Map Selected appeared first, there was no drop-down menu to select a map on the page behind it, and all of the UI elements disappeared when the Something Went Wrong message appeared.  
I rebooted, cleared cache, signed-out and back in, tried other browsers and tried from another computer with the same result.  Entering Maps through the campaign or directly and then selecting the campaign yields the same result.  I created a dummy campaign and loaded a few maps which seem to be loading just fine in there.
For the problem campaign, the map was Displayed, so the players can see the appropriate version of the map, and only a few hidden elements remain (and remain hidden on the player's map).

Working now!  Thanks!

Working! Thanks! What was the problem? So we both wouldn't do it again if possible