Recommend reading https://www.gnuradio.org/grcon/grcon17/presentations/symbol_clock_recovery_and_improved_symbol_synchronization_blocks/Andy-Walls-Samples-to-Digital-Symbols.pdf
Yeah, the MSK TED selections for the symbol sync block expect the constant envelope FSK waveform on the input. Demodulation from FSK to baseband pulses should happen after the symbol sync block.
