Syncro officially supports one browser: Google Chrome.
Having said that, 99% of the app works just fine in other browsers, such as Firefox, Edge, and Safari.
For those rare instances when something doesn't work as expected and you are using a non-Chrome browser, first try the same thing in Chrome. If it works as it should, then please switch to using Chrome. If it doesn't, please contact Support (at the top of this page, click Submit Support Ticket). Let them know you already tried it in Chrome and it didn't work there either.