Sitefinity Thunder has had support for 5.1.3270 since its the 126.96.36.199 version has been released (3 August). Please check your Sitefinity Thunder version. You can update your Sitefinity Thunder Visual Studio extension from Visual Studio by going to Tools -> Extensions Manager -> Updates, or by going to Visual Studio Gallery
to download the installation file manually.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items