No Dragon for Mac nor Enhanced Dictation

After "upgrading" to High Sierra I found that both Dragon for Mac (6) and Enhanced Dictation had ceased to function properly. As a disabled user, dependent on speech to text to use and control my computer, I strongly prefer Dragon for Mac – its feature set is considerably richer than that of OS X's Enhanced Dictation. I could survive using Enhanced Dictation, but after upgrading to 10.13 I found even that was no longer properly functioned, regardless of what microphone I used or whether or not Dragon had been loaded into the system. Has anyone had similar experiences with enhanced dictation or any suggestions? I've temporarily solve the problem by reverting to 10.12

I use an iMac (Retina 5K, 27-inch, Late 2014) within i7 processor and 32 GB of RAM, 1 TB SSD primary drive and 12 TB of external drives. As this machine is reaching its performance limits, I was sincerely hoping to upgrade to the new Mac Pro after it becomes available, but I have to solve this problem first or will eventually have to consider the complexities of a multi-Mac ethernet set up in my studio, or changing to another platform. I've a huge investment in music software (I'm a composer) and have happily used Mac's since the 80's – my first Apple was a Mac 512 K, so such a decision would be very painful. But, I can't afford to be stuck permanently at OS X 10.11.