7.10 edit note in task and note subject text becomes blank?

Noticed if you edit an existing task note, the subject is blank and can’t save without new subject?

Yes, this is a known issue

https://github.com/salesagility/SuiteCRM/issues/5327

there is a fix there if you need it immediately, or you can wait for the next releases early next week.

mysql Ver 14.14 Distrib 5.7.21, for Linux (x86_64) using EditLine wrapper
PHP 7.0.22-0ubuntu0.16.04.1
Apache/2.4.18 (Ubuntu)
Ubuntu 16.04 LTS