For the entire time I've run a store, I've had a problem with the "Send customer shipping notification" box seems to randomly uncheck itself.
If I notice it, I can re-check it, which is an annoyance, but not a lot of harm. It's especially problematic because I send a lot of packages untracked, and never go back in to the order to update the tracking info.
The problem is when I don't notice it, I put through tons of orders without notifying the customer that it's been shipped. Plus, there doesn't seem to be a way to re-send the shipping notice.
Customers don't like to order things & never hear anything, or have to write and say "I ordered something 4 days ago and it never shipped!". It's a bad look, even if you explain that the system screwed up.
If I had to guess, it seems like it defaults to unchecked if you have an order from Amazon or Ebay (which don't get shipping email notices). it's almost like shopify says "oh, I just created an order with no shipping notice, so from now on, no more shipping notices"
How can we fix this? It seems like a bug (and a pretty major one), not a feature.