Hi,
That has nothing to do with the thunderstorm like symbol,
and if I am right, you git a message from Acad if you try to insert the block, or not?
Try to insert one of the issue-blocks,
press [F2] and share the last lines with us.
>>" but others not able to drag and drop. "
Is there not a strange cursor symbol? And no message from Acad[F2]?
Please try to CLICK instead of drag&drop. Same problem?
>>"I have also brought and re-attached the path within file location in options. "
Thjat has n othing to do with the insert-tool of your toolpalette,
RIGHT-click on the tool, properties, check out the path and blockname there!
>>"But nothing, it only has happened when Auto Cad updated from 2020 to 2021."
If the block is present in the location (blockname, filename, filepath) it should work.