Hi mchamo,
Please set the below setting in your web.config file and try again.
<pages enableEventValidation="false" viewStateEncryptionMode ="Never" />
If it has not fix this issue, please create an example which can reprduc this issue and send it to
[email protected]. I will check it and get back to you as soon as possible.
Please include all necessary files in the example, so I can check it directly.
Regards,
Ken