Running Win 10 Pro 1803 current updates on all machines mentioned below.

The update to v18 seemed to work just fine. The OS2 came back online and was able to hear stations.

However, the web server was forever locked in "Loading" screen. Tried several browsers and computers. The OS2 is connected to a WiFi AP about 10' away and my computers are a combination of wired and WiFi.

Tried the tip you sent out a few days ago to hold the button while powering up the OS2. I had the v15 file ready to copy to the boodloader as with OS1. Windows acknowledged the new drive with tones, but that was it, the bootloader never showed up. I tried several times on 2 hardwired computers. But each time when I unplugged the OS2, Windows gave me the disconnect tones. I tried on 2 laptops, one wired and one WiFi. Neither laptop even acknowledged the OS2 as being connected even though it was going though it's bootloader process according to the LED.

I got the OS2 back to the AP mode with the button, and that's when things got really strange.

1) I had to reenter my information as though it was a new device.
2) The OS2 web server came up in my browser.
3) It told me that there was a new "bootloader" v5 that needed to be downloaded and clicking OK would take me back to the OS2 AP to install it. Clicked OK and found the OS2 AP on my iPhone. Apparently the BL update was to v6, not v5. All seemed to go well, except the OS2 was again a "new" setup. Went through all that and got it working.
4) Now, I tried to reload my recently saved profiles and here's more strangeness. Profile 1 loaded just fine. Imported 2, 3 and 4 and the last one, P4 was now in P1 on the OS2 with no others.
5) Selected P2 and was taken back to OS2 AP as there was nothing there. Went through the process and to set the OS2 back up again. Was able to import P2 into P2 and all was good.

I did not go through this procedure for P3 and P4 as I just copied them over and changed the servers and names. Another however. P3 shows correctly on the Status and Connectors pages, but it actually loads P1 information. P4 also shows correctly on Status and Connectors pages, but connects with P2 information. I tried to upload the openspot2-log.txt file, but it's not allowed.

Had to do some serious head scratching to figure out what was going on for sure. You might need to advise users that when the bootloader is updated, the device will be completely reset (at least mine did) and to EXPORT their profiles one at a time before preceding. Then fix the import section so each saved and properly named profile is loaded into the correct Profile on the OS2.

I might add that the v6 BL now shows in Windows with a single file - SRF-OSW.RDY