Why can't my HD1 set the RX frequency to 447.1875MHZ?

We know that Ailunce HD1 is the U/V dual-band ham radio. sometimes even if our setting frequency is within the frequency range, we can't set it successfully. Recently, I received a problem that the customer could not set the receiving frequency to 447.1875MHZ. What is going on?

It is caused by improper setting of the step value, and we only need to adjust the corresponding step value. Ailunce HD1 step value settings include 2.5K, 5K, 6.25K, 10K, 12.5K, 25K. When we set the RX frequency directly on the Ailunce HD1, we need to select the appropriate step value according to the specific frequency.