FM 2017 - Can't open non-DITA XML with a <topic> root

Hi,

FM2017, v14.0.0.361,  Windows 10

I finally installed FM2017, but hit an immediate showstopper. All of my XML (which is a lot) uses a <topic> structure similar to DITA, but it is not DITA. I have my own custom schema, template, structure app, etc. etc.  In previous versions, FM tended to assume my files were DITA, but I managed to stop that behavior by disabling all DITA-related API clients and removing all <topic> DOCTYPE declarations from the DITA structure apps. But in 2017, after doing that, I get the following error when trying to open my files:

Translator client (dita_fmapp) was not found. Operation could not be completed.

I know it's a long shot for anyone to know, but is there a workaround? Could it be that I suddenly can't open any of my files because FM has reserved the <topic> structure for DITA exclusively? If that's the case, I find that quite discouraging indeed.

Thanks,

Russ