Was the noise floor before the drop around -70db or -110db ?
If it was -70db and dropped to -110, i think it is a sign of a SoapySDR bug that shows once in a while in Linux/Ubuntu/Gqrx...
I would suggest tuneing above 30Mhz and adjust the samples/sec any where from 1,000,000 to 10,000,000.
I no longer can set a working S/sec of 1,000,000 or lower and have anythig shown where it should be below 24.5Mhz or so .. i forget.
I stick to around 5,000,000 samples/sec and use decimation to reduce the CPU workload .... USB throughput around 400K/sec ... around 800K/sec studders and 150K/sec crashes.