BPSK constellation decoding using gnuradio

I'm trying to decode a BPSK signal on GNU Radio and I'm struggling a bit so I hope maybe you will be able to help me.

The flowgraph I'm using is the following :

The bit frame I'm sending at the input of the flowgraph is :

1a cf fc 1d ff fd 55 53 33 3b bb a5 a5 8d 8d ed ed 6d 6c 93 6e 3b 68 5b 60 db 7e db 56 db 36 db b6 da 49 27 1c 74 2f 4f 94 ea 31 67 bc 8a 51 e7 3d 74 53 4f 3b 14 5b cf 25 14 73 cf 45 14 f3 ce ba e9 a6 9d 89 d2 1d 38 2c 5f 90 d5 c1 32 fc 46 af 09 94 1d cf d2 ea c6 99 09 dc 1d 2f d3 95 3a 33 a7 ba 75 a7 4d 8b 12 1b c7 da f5 26 b3 89 ba 1d a7 d2 75 38 b3 a1 ba 7d a7 52 74 c7 4e f4 e9 4e 9c e9 d1 62 c3 79 04 a3 f1 85 42 0c f8 11 5f c3 2a fb 99 5a 23 27 84 75 f0 b2 be 46 57 08 cb

As you can see, I'm using the "Constellation Modulator" block followed by the "Symbol Sync" block to simulate the modulation/demodulation. The decoding is then implemented by the block "Constellation decoder"

We can see in the picture below that everything seems to work perfectly : when I compare the input bit stream to the output bit stream the bits are synchronized

However when I open the file at the output of the flowgraph I'm unable to get the bit frame that I had at the input.

Do you know how I could fix this issue ? Any help is appreciated :)

Thanks and have a good day

Edit : I downloaded the module gr-satellites and used the block sync and create packed pdu and everything worked fine.