Are there any functionality issues for tall arrays with Matlab version 2016b?

I'm having a lot of trouble trying to work with tall arrays. There aren't a lot of resources out there, but I'm having issues with even the most basic functions. For instance,

>> x = find(~tt.YTW);
Undefined function 'find' for input arguments of type 'tall'.

On top of everything spreadsheetDatastore doesn't have any property on how to treat missing values. It brings in missing values as NaN, and if my variable of interest is of type double, NaN values create problems trying to convert the variables. Specifically:

Error using tall/gather (line 50)
Internal problem while evaluating tall expression. The problem was:

Unable to convert variable 'YTW' in sheet 'Sheet1' in file 'J:\Fixed _Inc\Internal\birtanderin\MS
Data\25-35\Book1.xlsx' to type 'double'.

I tried lots of different things but nothing seems to work. So, maybe the problem is with Matlab2016b? Please help.