Don't know if this is just coincidental or a result of the security update, but after installing the update on my S7, I was having trouble sending text messages. (Using native texting app) Some would go out in a second or two, others would stay with the red arrow spinning and not go out. Some had emojis, some plain text. Eventually, I installed Google Messenger, which, so far, has alleviated the problem.
Anyone else with a texting issue after the security update?