a question should ask Microsoft

Dear support,

this is not a joke, I should ask this question to Microsoft, but don't know how.

while I am working on a Quartus project, there a lot of .v files, and I want find a variable in all the files, so I use win10 file explorer, in this case, a variable "avmm_addr", in a file called fx3_reg_ctrl_hw.v, but win10 told me there are no file contains this string. I feel very strange, and did a little explore, I found that if I create a new file, pure_testfile.txt, and copy paste all the content in the called fx3_reg_ctrl_hw.v. and did a search again, this time win10 find the string in the called fx3_reg_ctrl_hw.v. I attached both files.

have this happened to anyone before? may be after many times zip and unzip, the text encoding already been changed to a strange one. but quartus editor, and win10 notepad didn't complain or warn anything wrong.

thank you for helping.

David