Windows 10 works fine with App Inventor. You did not provide enough information to give you any specific advice.
What new release? Version nb146i or something else? Were you ever able to build using Windows 10?
When the build fails, what happens? Do you show an error message? If so, what is the message?
Are you using Companion 2.35, the latest version of Companion?
How large is the aia file? Do you have more than 10 screens? Failure to build and save an aia are most often related to those two issues but the problem could be something else.
Are you using the latest version of Chrome? Have you cleared the cache?
Please answer the questions so we can understand something about your Projects so that someone might be able to provide you a way forward. Other users are not having issues building.