unity5.6.3p4+工具2.0.1导出场景报错XXX can't Readable...

unity: 5.6.3p4
工具：2.0.1
 
试图导出一个3d场景，提示所有贴图can't Readable,maybe you should cancel  Override for PC,MAC&Linux Standalone  checkbox.
我检查了这个选项并没有打勾，是咋回事呢...