I'm having a similar issue as described in https://www.varac-hamradio.com/forum/varac-hf-discussion-forum/no-rf-when-transmitting. I'm able to use my FT-847 with WSJT-X and VARA HF without any issues. However, if I try to use it with VaraC or FLDigi, I have almost zero modulation when transmitting. If I turn the power up to the maximum, I can see the power level fluctuate to about 20 to 30 W, where it's steady any other time.
I'm not sure what information you need, so I will attach screenshots of my VARA settings, WSJT-X settings, and VaraC settings. As far as I know, there are no menu entries in the FT-847 that apply to this (per the suggestions in the post I referenced), but I could be wrong.
Thank you for any help that you can provide me.
P.S. I apologize in advance if I should have resized the images. I'm not familiar with the requirements for the site.
I have reread your post a few times, I cant see where you listed how you get audio from the PC to the 847?