BIGIP VPN not working for GOTOMEETING

Hello, We have an issue with BIGIP VPN and would like to get some help. Thank you. We have our BIGIP Network access setup to allow users using Edge client to VPN in. We don't allow split tunnel and we are not using SNAT. We do have an internal web proxy (another vendor's product) and BIG IP is configured to use that proxy. Everything works fine except GOTOMEETING (global.gotomeeting.com). We cannot join any gotomeeting's meetings when using Edge client VPN in. What could be wrong? Thank you.