When you send a packet with the indicate to the mobile phone, the app running on the phone that is receiving the data should be sending a reply once they confirm that the data is valid/received.
Device send indicate with data -> Mobile receives packet -> Mobile either sends a response to confirm, or ignores to signal a failure/retry to the device -> device then sends a new data packet if no response was received or gets a confirmation packet if the phone sent the reply.
My guess if you are not receiving the data packet event on the Win 10 software is that you don't have it setup to query/receive the unsolicited indicate data packets from the cyble device?
Looking up the how-to on windows 10 bluetooth would be where I would start: Bluetooth GATT Client - UWP app developer | Microsoft Docs
Keep in mind, you need to be connected for a successful indicate exchange, so if the connection drops or fails then it won't work.