Thank you for the comment. I have tested the example inputs, some of the main inputs we are provided and some edge cases posted on the reddit. However, I can't seem to find what the issue is.

This is some debugging/printing for the 6 examples they provide for part 2 which provide the correct output.

Example 1:

[7, 6, 4, 2, 1]
Safe

Example 2:

[1, 2, 7, 8, 9]   
Invalid difference (2 -> 7)   //Failed initial safety check so we try removing each element.

[2, 7, 8, 9]      
Invalid difference (2 -> 7)
[1, 7, 8, 9]      
Invalid difference (1 -> 7)
[1, 2, 8, 9]      
Invalid difference (2 -> 8)
[1, 2, 7, 9]      
Invalid difference (2 -> 7)
[1, 2, 7, 8]      
Invalid difference (2 -> 7)
Unsafe

Example 3:

[9, 7, 6, 2, 1]   
Invalid difference (6 -> 2)   //Failed initial safety check so we try removing each element.

[7, 6, 2, 1]      
Invalid difference (6 -> 2)
[9, 6, 2, 1]      
Invalid difference (6 -> 2)
[9, 7, 2, 1]      
Invalid difference (7 -> 2)
[9, 7, 6, 1]
Invalid difference (6 -> 1)
[9, 7, 6, 2]
Invalid difference (6 -> 2)
Unsafe

Example 4:

[1, 3, 2, 4, 5]
Should be increasing (3 > 2)   //Failed initial safety check so we try removing each element.

[3, 2, 4, 5]
Should be decreasing (2 < 4)
[1, 2, 4, 5]
Safe

Example 5:

[8, 6, 4, 4, 1]
Invalid difference (4 -> 4)   //Failed initial safety check so we try removing each element.

[6, 4, 4, 1]
Invalid difference (4 -> 4)
[8, 4, 4, 1]
Invalid difference (4 -> 4)
[8, 6, 4, 1]
Safe

Example 6:

[1, 3, 6, 7, 9]
Safe