Performance SLA NOT appears when create a new SD-WAN Rule

Hello,

We have a pair of Fortigate 40F with FortiOS 6.4. We have added a second WAN access and need to balance traffic between them. When we try to create the SD-WAN rule with "Maximize Bandwidth (SLA)" option it requires a "Required SLA tarjet", but when we try to add it you're not able to select the Performance SLA (but it has been created correctly before).

If you check the attached image, the Performance SLA doesn't appear when you want to add it to rule (but it has been previously created and is listed on Performance SLA section.

Is this a bug of 6.4 version? I've tried with other browsers and same issue.

Regards!