Fixation ITI not working

I am trying to display a ITI fixation cross in my experiment but it will not run.
what am i doing wrong?
There is no error message.

The lack of an error message may be a bug in 2020.2.3 / 2020.2.4, if you update to 2020.2.5 then you should be able to get error messages and have a better idea of the problem! My first instinct is to check what your units are set to in the experiment settings, if your experimnt units are pixels then having a size of 0.5 is likely to cause problems.