The lack of ice indicates that it isn't causing ice to freeze in that block. The temperature in some blocks in the frozen ocean biome is not correctly interpreted by the weather visuals or the freezing/snow layer random ticks. Placing ice there does not cause it to start snowing. That location appears to have the wrong temperature returned when the code requests it.
Asthenic
The lack of ice indicates that it isn't causing ice to freeze in that block. The temperature in some blocks in the frozen ocean biome is not correctly interpreted by the weather visuals or the freezing/snow layer random ticks. Placing ice there does not cause it to start snowing. That location appears to have the wrong temperature returned when the code requests it.