At some later date I’d like to go a bit more into Felix and why I think it’s a great CAT tool, but for now I’ll just share a little point about using Felix.
Are you using Felix with multiple documents and now suddenly Felix isn’t registering translations? Apparently, as I’ve just discovered, if you’re switching between different programs (say, Excel and PowerPoint) and you switch Felix into Review Mode while in one program and, without switching back to Translation Mode in that program, attempt to use Felix in Translation Mode in another program, Felix gets stuck in Review Mode (which can’t register translations – the root of your problem). To fix things, you have to go back to the program you switched Felix into Review Mode and, in that program, switch Felix back to Translation Mode, after which it should register translations in that other program just fine.
For example, I was working on an Excel document and a PowerPoint presentation at the same time with Felix open. While editing the Excel document, I switched Felix into review mode. Then I close the document (and Excel itself) and tried to register a new translation in the PowerPoint presentation (which was still on Translation Mode). However, none of my translations would register and when I tried to switch Felix from Translation Mode to Review Mode and then back again, all I got were error messages. By opening up Excel again and switching Felix back to Translation Mode in Excel, I was also once again able to register translations in PowerPoint (and switch between Review Mode and Translation Mode without getting error messages, after shutting all the programs down and reopening them again).