Is there space on your C Drive ?
Looks like a bug which is fixed in 2018.1.5, 2018.2.2
When connected to SAP HANA, a "Memory Allocation Failed" error could occur when you added a level of detail calculation to the Filters shelf.
FIXED IN 2018.1.5, 2018.2.2
Read more at https://www.tableau.com/support/known-issues#aMPg2xfybKXZroBX.99
Please mark the answer as CORRECT & HELPFUL if it helps you so that it can help others as well
Well, i got space on 'C' Drive