Just to clear a few things up Paul. You were being moderated because you are a new member so some of your responses didn't show up until after we posted our comments. If you notice you're now a member and no longer a newbie so your replies will show up as fast as ours do.
Something tells me that it's not the new or latest firmware update that's causing your problem because by the nature of how things work you do have the April 15th 2019 update in your radio. Something else may have happened.
Whenever you hook up to Sentinel it's always a good idea to transfer your data card to your profile and save it first thing. Perhaps some settings were changed somehow when you transferred the data from Sentinel back to your data card on the radio after the firmware update.
For starters go ahead and check that all your service types are enabled and make sure that attenuation is not accidentally turned on. When trying to problem solve a head scratcher like this we should start with the basics.
I can almost guarantee you, the firmware itself is not your problem. Your post is the only one I recall seeing saying their sds100 (or sds200) totally quit receiving after the update.
Check which version of Sentinel you are using, it must be 2.03 with the firmware update. Check your programming, check your service types, check your location settings, etc.
Is it possible that the firmware update has toggled some settings from on to off or off to on? I don't own a scanner and have never done an update, but I have seen settings change after firmware updates on other types of devices.