Since the jump happens when you click, that makes the clicker (the mouse) the first suspect.

1. Conventional mouses get their balls dirty. When "mice had balls of steel" this just made the ball slip, and washing the ball or replacing it would fix lots (some said at leat half) of the problems IBM service people got called for, so a few decades ago IBM reps had lots of balls. Most rep offices posted a sign: "Have you checked your balls," at the exit door to remind their travelling reps to have lots of balls when they went out to do their rounds.

Since the rubber (coated) balls appeared, the dirt doesn't stick to the balls. The dirt gets on the rollers where it can accumulate, or can get distributed to where it interferes with the switches. The rollers can usually be cleaned. Rubbing the dirt loose with a toothpick or "cuticle stick" is a useful method. Once the switches get dirty, replacement of the mouse is the safest solution.

2. The communication between the mouse and the computer is a next suspect. Leadwires can develop intermittent wires that can drop a bit or add extraneous extra ones. "Remote" (wireless) mouses generally require an internal battery, and a "weak" battery can cause lots of unexpecteds. Connectors can get dirty and interrupt or modify the signals. USB mouses get power from the USB junction, and adding another USB device can sometimes cause "low voltage" to the mouse, or conflicts between devices. Recently sold computers often have four USB jacks that are really two USB ports with two jacks (front and rear) on each. Two devices on the same port often will work, but isn't really recommended.

You've pretty much done the usual things related to these suspects, so this is just going down the checklist.

John