It's been 3+ months and it doesn't look like @GunMediaSupport read the ticket because they are still giving out troubleshooting steps that won't resolve the issue as linked to in the Tweets below this post. They are giving out the same steps to uninstall and reinstall the game that any Agent at Microsoft / Xbox Support will provide because no one appears to understand the underlying issue. There is some sort or conflict with these DLC files that is causing them to uninstall on their own. Unless you have an Xbox and the disc in front of you to see first hand what is going on with this DLC conflict it may very hard to understand the problem people are asking about or even the workaround that I have been trying to explain for almost 2 years. I have not experienced anything like this with any other Xbox game.
I submitted another ticket today to jasonkillsbugs.com with a link to the workaround from my previous post. It's been almost 2 years and despite all my efforts I don't think it will ever be acknowledged let alone resolved. At the very least I think @GunMediaSupport should be telling people to purchase the Jason Part 7 Machete Kill Pack from Xbox Live and to keep it uninstalled because that is the only thing that works from the user end. I realize telling customers to spend another $2.99 to fix this issue is not something you would want to be doing but it's the only solution that works.
The workaround makes even less sense and the only reason it works is because Ilfonic didn't put any DRM on the paid DLC purchased or redeemed through a code on Xbox Live. This also means that the backer exclusive Clothing Pack #1 and Savini Jason have no DRM which is why people are still selling or giving access to that content without an actual code or xbox.com link. Since the disc DLC is loaded off the disc instead of a redemption code on Xbox even that can be shared an unlimited number of times by letting someone borrow the disc.
The other issue is in @GunMediaSupport telling this person to use the disc to install the game even though they also appear to own the game digitally. The disc will trigger a download of the latest build from Xbox Live and it is installed in the same folder that would be used for the digital game. The digital/physical game don't overlap so all you are doing is uninstalling and reinstall the same game to the same folder. There is no difference if you own the game digitally and on disc for Xbox. If someone only owns the game through the disc then uninstalling and reinstalling the game isn't going to resolve the underlying DLC conflict either. The only solution is to purchase the Jason Part 7 Machete Kill Pack on Xbox Live and to keep it uninstalled.
Update July 22, 2019:
I haven't received a response to the July 16th jasonkillsbugs.com report. I've sent several over the past 1.5 years and only ever received the auto generated "nobody likes bugs" email in regards to this particular issue.
@GunMediaSupport made another followup Tweet on July 17th, 2019 suggesting that you shouldn't have to purchase the DLC again. They do not understand the problem or why the workaround is the only solution. None of their troubleshooting steps will solve the problem and the workaround I have described in my previous post(s) is the only current solution. At this point in time I do not expect the underling issue to ever be resolved. The only thing I can suggest is to point people to the workaround post when it is inevitably brought up again because @GunMediaSupport doesn't understand the problem and is unlikely to ever fix it.