Based on the description, my first suspect is a faulty slave cylinder. The clutch systems on the newer vehicles are actuated hydrauliclly. At one point, you indicated it was in gear and the engine would rev. You may be getting fluid on the clutch disc.
I attached two pics below from the manual. Pic 1 shows the slave cylinder. It is behind the transmission bell housing. Note the red arrow. That is the hydraulic supply from the clutch master cylinder, see pic 2.
The clutch master cylinder does not have its own fluid reservoir. Instead, fluid is supplied by the brake master cylinder. So, don't laugh, but check the brake fluid and make sure it isn't excessively low.
Here is what I suggest. First, check the brake fluid level as mentioned. If it is low, refill it with DOT3 brake fluid.
Once that is done, check the clutch performance.
Next, look under the vehicle where the engine and transmission are bolted together. See if there is any evidence of something leaking. It would likely be at the base of the bell housing.
If there is no evidence of a leak there, under the hood on the firewall is the clutch master cylinder. Check for leaks there and check for leaks under the dash where the pushrod from the clutch pedal goes through the firewall.
Let me know what you find and if you have other questions. Also, to ease your mind, the transmission is likely not the problem. Instead, you can't shift when it is running because the clutch isn't disengaging.
See pics below
Images (Click to enlarge)
Friday, August 5th, 2022 AT 7:54 PM