Table problem in wordpress editor

Because there is no table support by default, I install a plug-in “MCE Table” to allow table editing.

My problem describe here.

Create an empty table.
Insert a line of text in the table cell, press enter.
Insert a second line of text in the same table cell, press enter.
How the table cell has two lines of text.
Save the post.
Save the post AGAIN. The two lines join together!!!

Initially I guess it is the MCE Table button cause that problem, I tried other similar table button plug-in, including TinyMCE Advanced, same problem.

I worked on this issue for days but no idea how to fix it.