I see the RETA-01 does not support function code 22 (0x16), which is used for masked bit writing to registers. This explains why your button will not set the bits as expected. There are 2 work arounds. If you only need to set 1 bit at a time in a register, then you can set the OutputType of the BasicButton to WriteValue, then set ValueToWrite to the bit value, for example to set bit 3 use value of 16
The other option is to use code to read the value, "OR" the bit to set, then write that value. There is a risk to this..... if something else changes the register value in between your read and write, then it will not write the correct value.