welcome to the forum. Did you read General Guidance and How to use the Forum?
Complete information is essential for a good answer.
In addition to the information you provided, I need to now what connection module you use, the board that has the booster electronics to produce the panel driving voltages.
And a clickable link to you display board or panel would be helpful, too.
296×128, 2.9inch flexible E-Ink raw display panel
same as:
It has the same controller as the GDEW029T5: IL0373
So I would expect you would see at least some reaction on the display.
what am I doing wrong?
You chose an e-paper panel that I don't have, and that is neither supported by GxEPD nor GxEPD2. 
But I don't know if this is the reason, with the information you provided.
There was at least one post that reported it doesn't work with settings for GDEW029T5.
Did you look at diagnostic output in Serial Monitor? The BUSY active times are helpful (in microseconds).
BTW: for Newbies or new projects I recommend GxEPD2.
Jean-Marc