Some of the random input test strings seem to include non-printing characters, that are not included in the expected results strings. Using something like strtok will pick up these characters, but if you try to printf to debug you won't see them. for example:

for words:
"m2 n3 oe4pwks nrrg9prjnr yi8etyad wrlymis1 7eld 6 yasdw5owy"

expected:
"wrlymis1 m2 n3 oe4pwks yasdw5owy 6 7eld yi8etyad nrrg9prjnr"

but got:
"wrlymis1 m2 n3 oe4pwks yasdw5owy 6 7eld yi8etyad nrrg9prjnr"

Copy and paste the input and expected strings from this example into one of the example test calls, and it will come back correct.

So it seems that to get the correct answer, you must fullly sanitize the input. The input strings are not clean!