SMS notifications aren't working when using hangouts for the SMS app
Sadly if you are on a version of android prior to android 4.4 sms messages can't be separated from chat messages when the SMS is integrated into hangouts as it stops the broadcast of new sms messages to other apps and also doesn't store the data anywhere that 3rd party apps can access

Luckily android 4.4 has changed SMS quite a bit and therefore in android 4.4 SMS and chats will be separated out

Version 3.14.x versions of the app require "hangouts - all notifications" to be switched on. Versions 3.15.x upwards don't have this dependency for sms.

I get an SMS/MMS and Light Flow shows I've got a SMS/MMS but also a new hangout chat message when I don't
Hopefully this shouldn't happen too often but the way notifications come in from SMS and Chat notifications is very similar and trying to split them is difficult and based on the timing of the two notifications getting broadcast from android. If the time between the two broadcasts is longer than 3 seconds then light flow will end up showing them both as separate notifications.

Contact specific hangout notifications don't work properly
There's some limitations to these as there's very little data available from hangouts. If you've only a few outstanding chats then it should work as long as the name shown in the notification matches the contact's name. Once there's a larger stack the contacts full name isn't available, so it's not possible to look up the contact.

I've a mix of chats, some contact specific and others not, but my "others" don't get noticed
Sadly it's not really possible when these are mixed to work out if new messages are from "others" or contact specific people if you've already got outstanding contact specific notifications.

If you have no contact specific chats outstanding and get a hangout chat for "others" then it will work to notify.

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