TRIM function or CHAR function? Or something I cannot figure out!

Hello,
I have thousands of row of data containing time. I need to know the length of time for a certain task. I have the start and finish times in two separate columns (Column A and Column B) but for whatever reason, the start time is not being recognized as time, unless I manually go into each cell in column A and delete a leading space, that doesn't even seem to be there. Please see attached.
If I place my cursor in front of the first number of the start time and press backspace, then enter, the text gets recognized as a time, and then the calculation is complete in column C. But unless I manually go in and press backspace for each start time, the length of each task cannot be calculated. I have tried everything I know and cannot seem to figure this out. Could someone please assist me?
I have tried TRIM, SUBSTITUTE, etc.

Thank you for your reply. Could you please clarify where the formatting issue is? I looked into formatting but could not seem to figure it out. Thank you for your help!!

Hi
Some data in column A has a extra char
Try this in C2 and copy down

Formula:

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Try this

PHP Code: 

=VALUE(B2)-IF(CODE(MID(A2,1,1))=63,VALUE(MID(A2,2,9)),VALUE(A2)) 


see the file

Please find attached sheet with formula. Hope this may resolve your issues

Formula to replace cell A
TIME(IF((FIND(":",A25,1))=3,MID(A25,2,1),MID(A25,2,2)),MID(A25,(FIND(":",A25,1)+1),2),0)

Formula to replace Cell B
TIME((IF((FIND(":",B25,1))=2,LEFT(B25,1),LEFT(B25,2))),(MID(B25,(FIND(":",B25,1)+1),2)),0)

You guys are amazing! I apologize for the late late reply! I was away this past weekend. Thank you Kamal and to Jose for your quick reply and help. It worked!! Thank you!!!