Convert text into date

You could parse out the string to create your datetime value. Something like this might work for you:

= with(
start: "2015-01-20 08:11:11.0",
split: split(split(split(local!start," "),"-"),":"),
splitInt: tointeger(local!split),
datetime(splitInt[1],splitInt[2],splitInt[3],splitInt[4],splitInt[5],splitInt[6])
)