Mosaic dataset is not always a multi-dimensional dataset. For example, if you see nothing for Multidimensional Info as the following figure shows, your mosaic dataset is not multi-dimensional:
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1. Right click and select Modify.
2. Choose Build Multidimensional Info.
3. After building multidimensional info, configure the allowed mosaic methods. Use By Attribute as default method.
4. Check Variables and Properties. All variables should appear.
By setting the default method, data will be sorted and presented by StdTime.