I don't usually make gravy but I did this time. It was tasteless.
The viscosity and texture were fine, but...
Used the pan drippings and potato/veggie water.
What did I miss?

Salt, pepper, garlic and onion?

Edited to add: I usually use canned gravy, lol. I pimp it up with the above. Mostly pepper. I love a peppery gravy.

Just another thought. If you have an overly spicy sauce, you can add potatoes. Maybe using potato water is cancelling out the spices? Not sure.

Included were onions cooked with the roast, powdered mustard and pepper.
We don't use salt.

  

One cube of  Maggi Beef or Chicken Stock should do the trick

I normally don't have any problem with my pan gravy when I fix a beef roast but when I do I cheat and add a can of beef gravy to it and it normally fixes the problem. Never tried the beef cube Jabra but will keep that in mind when I have a problem again.

Different gravies, different ways to make them--my late hubby Perry made some pretty good gravies. My fav no fail recipe for pot roast gravy:
When browning the roast before putting in crock pot, I sear it really good--almost burnt in a little shortening. Then I transfer the roast to the crock pot with a little water and either dry onion soup mix pkg or three or four of those oriental flavor seasoning packets that come in those cheap little ramen noodle pkgs. After the roast is finished I pour the juice from the crock pot into the pan which I had seared the roast in and get it hot and bubbly. I have this little cascade blender that holds about a cp-cp and half of water to which I add two or three heaping tbs of flour and shake it up (an empty small margarine tub with lid works in place of the little hand blender) I pour this shaken cold water and flour (be sure and add the flour on top of the cold water--not the water on top of flour before shaking) to the bubbly juices...stir, add water as needed and reduce down, adding more water if needed to right consistency, of course adding salt and pepper to taste. I've had pretty good luck with this way of making meat gravies.

My gravy is better than it used to be. The beef/chicken cube did it.
And as to onion soup mix, add it to home fries.

You can also cut about 2 pounds or so of potatoes into good-sized chunks, and toss them in a plastic bag with some veggie oil and the dry onion soup mix ~ spread in a single layer in baking pan ~ then bake at 400*-425* for maybe 35-40 minutes ~ stir around occasionally while baking ~ yummmmmmm!

Sooz

Sounds yummy!

Because we don't eat a lot of potatoes, we buy a little 2lb bag of baby red potatoes about every other week. Add a couple of tbls of olive oil, some fresh ground pepper and garlic (to taste) to a baggie and mush around to mix. Cut potatoes into halves or fourths, depending on size, add to baggie and mush around. I do it that way, instead of just shaking, so that it's more like a rub for the potatoes.

Put on a pan lined with tin foil and bake at 375 for about 30 minutes, turning the potato pieces once.

*reminder: red potatoes have less starch than white.

No added salt or mixes for us.