When I subscribe to your mod, BonusMap.vpk and MapIcon.zip containt the exact same folders and files. Not sure why.
Here's proof there is no Further Data even though I am subscribed to it: https://i.imgur.com/Ra90pah.png

Currently, Black Mesa cannot load map images in VPK files. That's why I included a ZIP file which contains all the map images.

But I've also included map images in VPK. I've done this because there is still a chance that CC will deploy a patch to Black Mesa and make Black Mesa able to load images in VPK. In the short term, for future updates

Those images won't hurt. Because BM can't load them anyway, and you'll extract map images as loose files, which have the highest priority of load order.

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But, still, you should have a grid of maps regardless of whether you extracted map images or not. If you didn't extract map images, you should see black map images, not a blank screen.

Here is a list you should try:

• Open the VPK file with GCFScape. If you don't see 'mapsinfo.bns' file in 'maps/workshopmaps' directory of the VPK file, you downloaded a corrupted file.
  
  • In this case, un-subscribe, delete the '362890 / 2867611331' directory, and re-subscribe.
    
• Move the VPK file to the custom directory. This will ensure that BM loads it.
  
• If nothing works, extract the content of the VPK file into the bms directory as a loose file.