So, please provide the valid 12 word seed and an example set of 16 consecutive words from the BIP39 word list such that none of those 16 words can satisfy the checksum requirement as the 12th word for the first 11 words of that seed.
OK. Here is an example.
The first 11 words:
half mango galaxy baby just mix able divide fog pattern cause
Words number 20 - 35 (16 consecutive words from BIP39 wordlist):
20. act
21. action
22. actor
23. actress
24. actual
25. adapt
26. add
27. addict
28. address
29. adjust
30. admit
31. adult
32. advance
33. advice
34. aerobic
35. affair
None of the words 20-35 can be used as the 12th word to have a valid seed phrase.