That's not one of the basic tests, copy/paste it to sample tests to see your code fail and debug it.

Basic tests
(9 of 9 Assertions)

Your code is wrong, not a kata issue. It fails tests like this one:

testing(longest_consec(["zone", "abigail", "theta", "abigail", "form", "libe", "zas"], 2), "abigailtheta")

The code in PyCharm gives you the correct result, but in the tests it is not correct. What could be the error?
print(longest_consec(['ahhhyaann', 'xxpppojta', 'ttiicccxnnnzz', 'eeeraafnbbddqii', 'jwwwsppc', 'uubddy', 'vvvaaaamww', 'zzzhbee', 'yybbbcjjqqqqq', 'kkyygnnn', 'oonghhh', 'vessh', 'ttllae', 'bbbqqqegggm', 'uxfffxxcuuurrrhh', 'ufrrrvvvnfffx', 'bbhhhnnn', 'lllcccekaa', 'zzqqquuugggpaaa', 'zzeeewwuuuvv', 'kkkuujqq', 'diiigggooo', 'rrruuuiiyyoooaaakkiiwww', 'qqdddhhbbuuu', 'cbvvqqqgggee', 'aaaveee', 'zzfffnnnrnoo', 'tttaaauupssswfff', 'nnnnllled', 'jaaaennnyyp', 'llljuuhhhww', 'wwzzzmmmk', 'swwwjjn', 'ccnnnqqqfffoooko', 'obbkkxxddd', 'qlluujjcccjssseeep', 'aamjj', 'aaarrrmmmbhh', 'brrrdvvc', 'mmmtuu', 'fffssnnneuuq', 'rrtttv', 'ggtbbbttooh', 'nnnwwtttlfff', 'ppttttwaaa', 'fnntccckllttt', 'ggooouppp', 'vvhhhdddso', 'xxxnnooqqfjjj', 'cztf', 'fffuubbbb', 'crrrnn', 'sswfooff', 'jjjgggkktttaxxoozz', 'llttyy', 'ymln', 'kkggyyygvvvvvf', 'hhfffimmmvvvsss', 'xjjjkyfqq', 'jyyssddlla', 'hhhrzzzttt', 'eewwbeeq', 'xxfffccbpvvvu', 'ffvvvggggggvf', 'ffofffdddvvqq', 'ffxpppssstttl', 'yyymmkkkzziii', 'ygga', 'feetttcc', 'rrrjdddzqqqfgg', 'vvvssuuuj', 'ssbbbccqkk', 'sazzzvvrrrexbb', 'kkwwwrycs', 'fiyyyaaa', 'sbbbpp', 'oooeeennnoo', 'uuuuuqqqw', 'ndddqqqkh', 'qqqoorm', 'kenncccllqqtx', 'kcccellljsslll', 'qvvvvmmmee', 'eeennnqqqnmmm', 'eovgkkkhhh', 'mnnnkkaaa', 'hhhlbbeeepppw', 'qqqaabbbpppht', 'iicd', 'kkiikj', 'riiii', 'fffoccclwee', 'xxdxxzzzkkzzz', 'hhhccuweeekkk', 'zzzoobbfffllj', 'jkkkggg', 'dvuu', 'iibffwwll', 'yyvff', 'ahhiiipppqqq', 'zzppcccffcchhmmmm', 'wwwxxxpppnnnbyyy', 'ppnnniyyfffn', 'qqzziiu', 'xxxmmmvnnnoww', 'yyzxxl', 'bbjwwtttdp', 'cccnefooojttt', 'mppps', 'mmaasaa', 'wwweeezkqqqo', 'unnoddttt', 'kkjjjcccaaayyy', 'qqehhn', 'rryyjjjfgggvvv', 'gxi', 'pppbbbssjh', 'xiddddhh', 'eeotttfffcc', 'kkkjhooovvvvv', 'qfcccvvvjjj', 'xxxqcjjjummooo', 'reyyy', 'fooeeesssw', 'ttrrpppeyyy', 'hhhdddmmmgnn', 'hrnyyyyttz', 'ddqqaayyyyy', 'hhvaaawwnnnooo', 'ccsskkkuu', 'aaffqqhssjjjjp', 'leeeraaabbkkk', 'vvvyyshhhssse', 'fzzmmmfff', 'fvooyyygbbdnppp', 'hhsssdddhhh', 'pjjjccclllsss', 'yyydddaaauuubbrrrvv', 'xxxrrn', 'lllzzzxxooqqa', 'yyyvyyyr'], 17))

uxfffxxcuuurrrhhufrrrvvvnfffxbbhhhnnnlllcccekaazzqqquuugggpaaazzeeewwuuuvvkkkuujqqdiiigggooorrruuuiiyyoooaaakkiiwwwqqdddhhbbuuucbvvqqqgggeeaaaveeezzfffnnnrnootttaaauupssswfffnnnnllledjaaaennnyypllljuuhhhww