4-wheel-drive is not engaging?

If the front drive shaft is spinning, then you have an issue in the front differential.

I would suggest removing the cover and spinning the front drive shaft to find out if there is movement inside the cover.

Here is a guide that will help with this.

https://www.2carpros.com/articles/differential-service

This is on a rear differential, but the process is the same.

Once the cover is off, just have the vehicle on jack stands and spin the pinion and see what is happening inside the unit. However, I suspect you will find the issue when you remove the cover.

https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely

Please see the info below. Please let us know what questions you have. Thanks

Also be aware there's a vacuum-operated shift fork on the rear, right side of the front axle housing. Remove the vacuum hoses with the engine running, then check for vacuum at one of them, then on the other when shifting the four-wheel-drive lever. You can also feel for movement inside the housing when a helper operates the four-wheel-drive shifter.

The vacuum motor should be working because that is what turns on the "4WD" light. I suspect something came apart inside the housing. Here's a drawing showing what's inside.