We have a customer where we installed a Exchange 2013 server. Everything is running fine but when using tasks in OWA in combination to normal Exchange client, we see that they don't synchronise.

When opening task in OWA, it will sync to Outlook but it's empty task, only header info
When changing task in outlook, it will not sync to OWA
when changing task in OWA, it will appear empty in Outlook
When opening task in Outlook, it will appear in OWA

When we do same with mail, no problem, they all sync fine.

I've searched the entire internet and no luck yet, anyone else came accross this issue and has a solution?

We are on the latest outlook client.

Thanks!

What service pack and update rollup are you running?  You should make sure you're at the latest.

Hi TomHuis,

Thank you for your question.

We could restart IIS on all Exchange CAS server to check if the issue persist.

If not, we could refer to the following link to rebuild EWS virtual directory:

https://technet.microsoft.com/en-us/library/ff629372(v=exchg.141).aspx

in addition, check there are any related errors in event logs and send them to ibsexc@microsoft.com for our troubleshooting.

If there are any questions regarding this issue, please be free to let me know.

Best Regard,

Jim