Hi 信清 高志,
Thank you for reaching out to the Microsoft Q&A platform.
Please check that N-series VMs might not be available in the region where your WVD is deployed.
Check subscription might have reached its quota limit for N-series VMs.
Ensure that the VM size you are trying to resize to is compatible with GPU acceleration with the required series.
To enable GPU acceleration, you can consider using other GPU-optimized VM sizes supported by Azure Virtual Desktop
Please find the below documentation for your reference:
I hope this information is helpful. Please feel free to reach out if you have any further questions.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Thank You.