Recently, we were working on a custom workflow activity which takes Whole Number as input, process it and returns a String as Output.
After developing it we tested it and it was working fine.
Later, we wanted to change the data type of input parameter to Decimal so that we can take care of fraction as well.
We changed the code accordingly and data type of input parameter in custom workflow activity code and deployed it to CRM. However, the data type of Input Parameter was still Whole Number.
FIX: To fix this issue, we unregistered the workflow activity using Plugin Registration Tool(removed it’s dependency first) and deployed the custom workflow activity again using DEV ToolKit. Now, the data type of input parameter appeared properly.
Hope it helps !!
Ajit Patra 