Can't Save Edited Files

Now with version 5.7.6 on Windows 10, I am on a new machine and unable to save edited files on the remote Linux machine.

The text files open fine, but when we try to save, they are stuck in the queue.

Note that we are able to transfer the files by clicking on them in the queue and selecting execute now.

However, selecting various options, we are unable to disable the background queueing, or to disable the queueing either.

You probably have Enable queue processing by default turned off:
https://winscp.net/eng/docs/ui_pref_background