For bitmaps with over 102 elements, there is a bug in the (de)serialization.
old_bm = new_bm ? 0
Card(old_bm) = 102
Card(new_bm) = 60
old_bm:
{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101}
new_bm:
{0,1,102,116977,131073,262147,393221,524295,655369,786443,917517,1048591,1179665,1310739,1441813,1572887,1703961,1835035,1966109,2097183,2228257,2359331,2490405,2621479,2752553,2883627,3014701,3145775,3276849,3407923,3538997,3670071,3801145,3932219,4063293,4194367,4325441,4456515,4587589,4718663,4849737,4980811,5111885,5242959,5374033,5505107,5636181,5767255,5898329,6029403,6160477,6291551,6422625,6553699,13500672,16777216,1610612736,-2147483648,-1342177280,-923676672}
It seems that the serialization always works well for bitmaps with less than 102 elements, and always fails for bitmaps with more than 102 elements.