hi there,
For redirects, the file is just _redirects not _redirects.txt (no file ending) so the latter won’t work.
I’m not sure at the moment where the issue is occurring that you are describing, but
This Support Guide contains a ton of useful debugging tips that can likely help you solve your problem 
If you are still having problems, please provide as much information as you can on what you have already tried, what your build settings are, your package.json, etc. Thanks!