Looks like you are using and old version of DW.
We have restore complete Find and Replace functionality of DW CC 2015 in latest DW versions(Since 17.1).
I would recommend you to try latest DW and try using enhanced Find and Replace.
more details => Find and replace text, tags, and attributes
Do you see this consistent happening? if yes, could you please share your test files and steps to recreate this issue?
We could definitely investigate this if we could see this happening locally.
I am heavy "find & replace" user, and the current interface is frustrating. The UX for the current search interface and how it works seems to be a riddle to me.
Either it is is totally not working or all of a sudden I became an alien to DW.
I can share video or what I am doing - Or one of you are free to access DW remotely.
I use it in Mac OS Sierra. I am unsure if it could be an indexing issue.
We have two components of Find and Replace now:
1. Ctrl+F which invokes Quick Search Bar only for the current document
2. Ctrl+Shift+F invokes Advanced Find and Replace dialog which works for find in- Entire site, folder, open documents etc.
If you are facing any issues in the functionality, please share video captures/screenshots/files you are working with workflows so that we can help you better.