Steps to reproduce:

1. Edit or create a page
2. Add a table with some data
3. Add another table with some data. Specify the same number of rows and columns as the first table.
4. Try to copy a row from the second table and paste it in the first, using ctrl-shift-c and ctrl-shift-v. Nothing will happen.

Expected behaviour:
The row from the second table should be copied and then inserted into the first table.

Note, I tested this in Chrome and it works.

Workaround: Use the table toolbar