Not sure I have full absorbed this, but maybe. You have a 3 ph trans with Y connection. Output side likewise, with added three ph rectification.
You have tried energising across two phases and hoped to find voltage across the third, but nothing. Try adding a capacitor AND a slave motor, to produce a simple rotary converter. (If you manually spin it -not advised - you may not need capacitors) I suspect you will now get the sort of output you require.
Seven years ago I developed a 230v to 415v single to three phase converter using a slave motor, without a transformer. You can see in action here:--
https://vimeo.com/130990021
Les.