Display mode became box mode only after mergeing a new set of edges, no matter which.

[s3934304]

There's a problem with my fusion Form function. After I finished making the faces and ready to merge them to complete a closed edge body, the view mode just becomes box mode no matter which edge that i want to merge, and it won't switch back to smooth mode anymore unless I ctrl z.

Here are some photos:

There is a model attatched below.