ImportError: undefined symbol: _ZTIN2gr10sync_blockE

[PRANAV HINGORANI]

I'm trying to make my own iio block. For learning, I tried making my own
FMComms2 source from gr-iio. It seems like I'm getting some linking errors.
I'm using Ubuntu 20.04.6 LTS.

c++filt _ZTIN2gr10sync_blockE
typeinfo for gr::sync_block