macOS Monterey 12 - Couldnt Start Dropbox

I ran into the same issue.

bn.BUILD_KEY: Dropbox
bn.VERSION: 134.4.4115
bn.constants.WINDOWS_SHELL_EXT_VERSION: 51
bn.is_frozen: True
Traceback (most recent call last):
  File "dropbox/client/main.pyc", line 816, in wrapper
  File "dropbox/client/main.pyc", line 6537, in finish_dropbox_boot
  File "dropbox/client/message_queue.pyc", line 313, in _wrapped
  File "dropbox/client/main.pyc", line 6070, in _init_components_for_account
  File "dropbox/client/main.pyc", line 5994, in create_sync_engine
  File "dropbox/sync_engine_boundary/factory.pyc", line 226, in make_sync_engine
  File "dropbox/sync_engine/nucleus/classic_client/sync_engine.pyc", line 278, in __init__
  File "dropbox/sync_engine/nucleus/classic_client/modern_client/modern_client.pyc", line 245, in __init__
  File "dropbox/sync_engine/nucleus/classic_client/modern_client/base.pyc", line 152, in __init__
  File "dropbox/sync_engine/nucleus/classic_client/thin_adapter/in_proc.pyc", line 209, in __init__
  File "dropbox/sync_engine/nucleus/classic_client/thin_adapter/in_proc.pyc", line 520, in _init_new_engine_locked
  File "dropbox/sync_engine/nucleus/thin_client/client.pyc", line 188, in __init__
  File "desktop/extensions/nucleus/nucleus_python.pyx", line 76, in nucleus_python.NucleusSyncEngine.__cinit__
nucleus_python.SyncEngineError: "Initializing engine |>> Initializing filesystem |>> Attempting to register icons |>> Opening dst |>> open syscall |>> Permission denied"

I tried all the solutions folks have posted but nothing seem to work.  Dropbox has access to full disk, I have re-installed, rebooted several times, deleted the dropbox folder in application settings...  Nothing seem to want to work.

This is on an iMac 2017 running Monterey 12.0.1.  I performed a clean install of the OS today and then used migration assistant to bring my user folder over.  

Dropbox works fine for the other user on this iMac (also created via migration assistant).