08 Silverado reverse wont engauge

I have an 08 Silverado quadcab, 5.3iron, 4x4, about 7,000 miles. After startup when placed in reverse the truck won’t shift, also the underlining indicator will not be illuminated under the R. Also the cruise won’t work either, nor the driver side window. This of course happens sporadically. Took to the dealer today and everything checked ok. Has happened about 10 times. One or two restarts so far has always corrected the fault. Any ideas? Hate to have this problem with such a new truck. Thanks for any help.

most likely the range switch is at fault or has a bad connection