I'm trying to run your code. I'm interesting on the part of the pointer (I want to test Siamese Networks on OpenVINO and NCS2) but I obtain that error. I'm using tensorflow == 2.0 as you commented but in that versions seems not be the parameter 'fn_ouptut_signature' on the tf.map_fn function (that there is on tensorflow == 2.4.1).
Have you had this problem when you run it? If no, any ideas?