I get this message on about 95% of my files, however never had a problem with infuse 4. Infact when this started I could go back to infuse 4 and play them but I thought I had it working so deleted 4 and the problem persists. Have used other devices on my network to stream and everything’s okay. Using iPhone 7 on latest iOS.
If you have a chance, can you send us an email from within the Infuse app? This will help us track down what is going on in your case.
Details on doing this can be found here. https://support.firecore.com/hc/en-us/articles/215090927-Troubleshooting-and-Getting-Support