Notarized app is hindered/blocked

I have an app that is being blocked with "...can't be opened because Apple cannot check it for malicious software" on Catalina.

This dialog:
https://support.apple.com/library/content/dam/edam/applecare/images/en_US/macos/Catalina/macos-catalina-alert-unsigned.jpg

As far as I can tell, my app should not be getting blocked with this dialog. I have check my app like this:

% xcrun stapler validate ...app
Processing: ...
The validate action worked!
% spctl -a -vv ...app: accepted
source=Notarized Developer ID
origin=Developer ID Application: ...
% codesign -vvv ...app
--prepared:...app/Contents/Entitlements.plist
--validated:...app/Contents/Entitlements.plist
--prepared:...app/Contents/MacOS/launcher
--validated:...app/Contents/MacOS/launcher
...app: valid on disk
...app: satisfies its Designated Requirement
% codesign -d --strict -vvv  ...app
Executable=...
Identifier=...
Format=app bundle with Mach-O thin (x86_64)
CodeDirectory v=20500 size=414 flags=0x10000(runtime) hashes=4+5 location=embedded
Hash type=sha256 size=32
CandidateCDHash sha1=261b5f7c3afcfdab1dd0ab99657a49bd34342f7b
CandidateCDHashFull sha1=261b5f7c3afcfdab1dd0ab99657a49bd34342f7b
CandidateCDHash sha256=443f7e562041dd0fdb144f2530b5dd854b64415c
CandidateCDHashFull sha256=443f7e562041dd0fdb144f2530b5dd854b64415cca203899e082e166c82d8b37
Hash choices=sha1,sha256
CMSDigest=01fb528e10bebc4effa7a034e90528c63c1354295c7df386d4da319327c827c1
CMSDigestType=2
CDHash=443f7e562041dd0fdb144f2530b5dd854b64415c
Signature size=9041
Authority=Developer ID Application: ...
Authority=Developer ID Certification Authority
Authority=Apple Root CA
Timestamp=Oct 15, 2019 at 9:42:17 AM
Info.plist entries=15
TeamIdentifier=...
Runtime Version=10.9.0
Sealed Resources version=2 rules=13 files=489
Internal requirements count=2 size=180

These commands were run on a Catalina machine that didn't do the signing and notarizing.

During notarization, I do have various warnings, but the notarization result includes so I assume my app is ready to run on Catalina (for now).

"status": "Accepted",
"statusSummary": "Ready for distribution",

What else can I do to diagnose?

Thank you.