There's some network errors reported in the log file.
If you haven't tried this yet, please try work-around 1 in the below link for the two designs that are having difficulties syncing. If you're not concerned with losing existing pending upload, you can use work-around 3 to manually remove the file from the upload queue.
https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/Fus...
Network Errors:
20171030T110133 E 1509354074435 1509354092340 POST https://ssl.google-analytics.com/collect 35 schannel: failed to receive handshake, SSL/TLS connection failed
20171030T110146 E CloudBrowser failed request - exception: WinHttpReceiveResponse: 12152: The server returned an invalid or unrecognized response
...
20171030T110257 E 1509354165140 1509354176659 GET https://developer.api.autodesk.com/wipdata-serv/storage/v3/lineages/urn%3Aadsk.wipprod%3Adm.lineage%3AzmuldkzKT4OC9zyyaUJPLQ 6 Could not resolve host: developer.api.autodesk.com
20171030T110257 E Call to WIPService::getLineageTip failed with Status: 0. Result Code: 0
20171030T110257 E URL: https://developer.api.autodesk.com/wipdata-serv/storage/v3/lineages/urn%3Aadsk.wipprod%3Adm.lineage%3AzmuldkzKT4OC9zyyaUJPLQ
20171030T110257 E Response Data: Could not resolve host: developer.api.autodesk.com
20171030T110257 E Failed to download file from A360.
20171030T110257 E A360 Error Message - Failed to download file from A360. - Click here to view error message.
From the errors, I'm not sure what is causing the communication issue. However, there's a guide to troubleshooting network connectivity issues for Fusion 360 in the below link. You may want to make sure that you have the correct exceptions added for the ports and domains that Fusion 360 requires to operate.
https://knowledge.autodesk.com/support/a360/troubleshooting/caas/sfdcarticles/sfdcarticles/Network-C...
If you can share more information about the network configuration (proxy, firewall, anti-virus software, etc..), it may be helpful.
If you're on a laptop and moving between networks, sometimes the below suggestion can be a helpful thing to try.
https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/Fus...
20171030T113800 W MessageBox Warning: Unable to validate a security certificate. Many times this can be triggered by proxy servers, security software, or out of date OS patches.
Please visit the "Network/Server Verification" preference page if you would like to change this setting.
For that last warning message, last week, I was able to resolve this warning by changing the Server Verification setting in the Network Preferences to "Warn when accessing..." See the image below for further clarification.
What setting are you using currently?

I hope this helps!
Thanks,
Nathan Chandler
Principal Specialist