I just received my new Ruuvi Pros (both styles, 3-1 & 2-1). They look great! Solid design.
I know my Google Pixel 3 has a sub-par bluetooth receiver, but I get very slow update rates (10-15mins) from the waterproof (2-1) sensor versus the usual 0-2sec updates from the standard sensors, and the 3-1 Pro, at a distance of 1 meter. Can the sealed housing of the 2-1 Pro affect the Tx Power and RSSI? I’m currently reading 4dBm and -59dBm at 1 meter distance.
As I wrote my post, the 2-1 Pro starting broadcasting at 0-2sec. Did it know i was talking about it? 
I’ll keep an eye on it…
Most phones share antenna with WiFi and Bluetooth, so the Bluetooth reception depends a lot on WiFi activity. It’s possible that your phone was downloading some updates in background etc.