Rush won't export on my phone

I have used rush for ages with no problem apart from occasional crashes but the last couple days I've been trying to export videos and it just says exporting but never gets above 10%, it doesn't crash or stop loading it still says exporting just never gets past 8-10% I wondered if it was storage or cashe but nothing else is open on my phone and I have plenty of storage and tried all the usual restarting, opening different projects etc.