This is basically an extension of Andre’s post -> https://andz88.wordpress.com/2015/05/25/australian-data-centre-bug-workaround-invalid-argument-in-workflowbusiness-process-flow-editor/
This issue seems to be affecting organisations created in APAC region as well, if they have their Personal Preferences -> Format set as English (Australia).
I am running v7.1.0.1086.
The resolution is the same as described in Andre’s post. Change the Format to English (United States).
Dreaming in CRM & Power Platform 
[…] Andre Margano blogged about the error in Workflows and Business process flows: “Australian Data Centre Bug Workaround – “Invalid Argument” in Workflow/Business Process Flow Editor” and Natraj Yegnaraman found the same error during a data import: “Invalid Argument – Data Import“. […]