Hi,
It looks like I have similar problem.
Yesterday I successfully created a new design and everything was working well. Then I tried to generate a milling toolpath in the Manufacturing workspace, and encountered an issue with CAM Kernel. I'm using Windows 7 (I have several reasons for that), so to solve this issue I had to replace camkernel.dll with older version. This required a Fusion 360 restart, and an automatic update happened. After that the problem with opening old designs appeared.
Now I'm able to open only the designs which are cached locally on my PC, local *.f3d files, and local *.f3z files after uploading them. My first thought was that this issue was related to usage of Windows 7, but today I found this thread with very similar problem on Win 11...
I've already tried clearing cache, restarting my PC, opening previous versions of designs etc. with no success. Everything worked just fine before the automatic update (I think that was a version from the end of January) and everything broke after it.
I'm not sure this is related to the issue, but in the log file I see errors like this:
20220221T151149 E 8688 DOWNLOAD 35 https://cdn.us.oss.api.autodesk.com/com.autodesk.oss-persistent/us-east-1/0e/6a/38/51d09e086e96d9b96d89c8f59cfee0444e/fusion.prefs.login?response-content-type=application%2Foctet-stream&response-content-disposition=attachment%3B+filename%3D%22BVPMR3YWPB7V__gmail207819_RecentsWithoutSearch_1.json%22&Expires=1645445627&Signature=ahTZmyXg-6TYLdZNg4D1yhWBtFXaaw0HPYLBfSwbm5ZLghcIZDGNmeJyIgCBHrsxsHvlpiuVToeMbc~oy4YX2~a14dqCAGwZrf-1cC-VnAlBdkGAODjY2sytazmWH1ruESLO1dOu~UVNT7KUjl5laguI~ggqsFKZs44rRZMugYl6J~qi3FLVEQZkoeF2xRN5pnyG0zFQ1~tCqpkw4UbqqbvpDski4Kb2JGNN28buq5kV9hBW5ne~I9iqemMOGhB-emyk5s4xICe8BMb13jEMiGz1u3X0ObZWJfvNImacrspjdf4KOIQhsZMeOAzuJ~eslzRQVgYDZgtO9CX4Dar06w__&Key-Pair-Id=K5HRZD7MMO1U9 dt=0.12 schannel: next InitializeSecurityContext failed: SEC_E_ILLEGAL_MESSAGE (0x80090326) - This error usually occurs when a fatal SSL/TLS alert is received (e.g. handshake failed). More detail may be available in the Windows System event log.
when trying to open on old design. Opening the link from the log in a web browser gives no error - a JSON file is successfully downloaded.
Arseniy