Hi Joe,
You mentioned using the tung oil (or the mix?) before with good results but this time it is not working. Is that correct? If that is the case it may be the thickness of your coats and the humidity. I've used a tung oil, polyurethane, and turps mix as a sealer and then "polymerized" tung oil as my top coats for >20 years. It is my favorite mix unless I want to use an actual varnish. Anyway, none of the ingredients you describe should cause any problems. However, pure tung oil (no solvents, driers, or treatments) can take a long time to dry. I use polymerized tung oil, a process in which it is heated so that it dries quickly. Lee Valley, Garrett Wade, and Sutherland-Welles sell the stuff. There are also products on the market called "tung oil finish" that contain no actual oil, just derivitives combined in a varnish. You do need to know what it is you have with respect to the tung oil. That said, generally if finishes can be thinned with the same thinner, they will be compatible when mixed. My advice is to be patient and let the stock have plenty of time to dry.
dave