hi all:
i met this issue too. and finally i solved it. i put my solution here and hope it can help someone who also meet this issue.
find imx-yocto-bsp/sources/meta-imx/meta-ml/recipes-nnstreamer/nnshark/nnshark_2021.10.imx.bb
edit it as below:

use "bitbake -c cleanall nnshark" to clean nnshark first and then use "bitbake nnshark" or "bitbake imx-image-full -c populate_sdk" to build again.
in my case, i failed at the first try. i don't know why. maybe due to the bad network? but i clean nnshark and rebuild again, it success.