INDEX/MATCH function eventually changed the location of the source file

Hello,
I am working on a workbook which contains INDEX/MATCH formula in which the source is coming from a different file.
It was working perfectly for a couple of days and eventually it stopped. I checked the formulas and noticed that the
formula on the INDEX/MATCH automatically changed. See the difference between the two below:

Original Formula:
=IF(ISNA(INDEX('\\DCSERVER01\[BERSACCOUNT1.xlsx]Sheet1'!$A:$A,MATCH(B4,'\\DCSERVER01\[BERSACCOUNT1.xlsx]Sheet1'!$C:$C,0))),"",INDEX('\\DCSERVER01\[BERSACCOUNT1.xlsx]Sheet1'!$A:$A,MATCH(B4,'\\DCSERVER01\[BERSACCOUNT1.xlsx]Sheet1'!$C:$C,0)))

The New Formula:
=IF(ISNA(INDEX('C:\[BERSACCOUNT1.xlsx]Sheet1'!$A:$A,MATCH(B4,'C:\[BERSACCOUNT1.xlsx]Sheet1'!$C:$C,0))),"",INDEX('C:\[BERSACCOUNT1.xlsx]Sheet1'!$A:$A,MATCH(B4,'\C:\[BERSACCOUNT1.xlsx]Sheet1'!$C:$C,0)))

Things to consider:
1. No one can modify the file since I am the only one who has access of this file on the network.
2. The cells where these formulas are encoded are all locked
3. The workbook is locked and you cannot click on the locked cells
4. The workbook is password protected


Thank you so much.

It looks like you had your workbook with the index/match formula in it, opened the BERSACCOUNT1 template and saved a local copy on your c drive and then saved the workbook with the index/match formula in it.

Edit: As to what to do, you could try using indirect to hard code the reference locations but it would make it a bit messy.

@ yudlugar, thanks for the reply.

i tried to bring back the original formula but doesn't work as expected.
i get blank cells instead of showing the values.

-This is what i get when it was still working fine
003.JPG

-And this is now i'm getting after bringing back the original formula... nothing, just blank cells
004.JPG

i'm confused of what is really happening here. how does the formula automatically changed
when the workbook is actually password protected? i unlocked the workbook and brought
back the original formula and now i'm getting blank cells instead of showing the values?
how come?

It's hard to provide much input based on a couple of screenshots..

by the way, the cells filled with green color is where the INDEX/MATCH is encoded.
the cell filled with yellow is where i type the value.
the cells filled with green is locked so there is no possibility that any one can mess
up or change the INDEX/MATCH formulas.

do we need to take into consideration the following instances on why this happened?:

1. the server (where the source file is saved) went down.
2. the source file is a shared workbook.
3. someone is working/encoding pieces of information on the source file.