Well .. I can here!
Are you using a recent version (I think i remember there was such issue L-O-N-G time ago …) ?
If there is some problem with latest version (se announcement or 5.14 RC at the top!) then please explain in detail:
1) What does the table look like at the start. (screenshot or dump)
2) What are you doing EXACTLY … words .. screenshots .. flash movie 😆
3) And what happens (or not)?
Always if possible give a 'reproducable test case'. Actually at bugs.mysql.com the don't even consider reports without such 'reproducable test case'. They are closed automatically after 30 days! We are (sometimes) a little more flexible here. …
But as said I can easily ALTER TABLE and SET DEFAULTs in 'one shot'. So please explain yourself better! And try a recent build first if you did not.