Problem:

If you have a number in your machine readable name for your subscription type (eg: 3_month_sub) and try to add subscription through rules (using the Create Entity action) the rule fails with the following output in the log:

2.933 ms Unable to get a data value. Error: Invalid data value given. Be sure it matches the required data type and format.
2.977 ms Unable to evaluate action entity_create

Workaround:

Make sure you have no numbers in your Machine Readable Name of your subscription type.