I trade with Oanda as well and use their MT4 platform. When I download indicators from their website they go directly into the indicator file and are available for use immediately without having to restart the platform. I am running Windows 10. I know this doesn't solve your problem but is does show that as of yesterday the indicators from Oanda are, in fact, not compromised in any way. Maybe one of our platform specialist here can help you with your individual problem.