If your Gmail signature is not displaying correctly, you probably need to disable the "Plain Text" mode.
Here are the simple steps to follow to solve this problem:
Example of the problem:
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Instead of:
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The Solution :
This is probably due to "Plain Text" mode, to disable it go to "new message".
You will need to uncheck the "Plain Text Mode" option and start a new email.
Setting not OK:
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Setting OK:
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Your signature should return to normal.