JTAG is not recognized by MAX® 10. Is it related to the fact that the Exposed Pad on the back side of the EQFP package is not connected to GND?

Yes, the Exposed Pad on the back side of the EQFP package must be connected to GND.
If it is not connected to GND, the device will not be recognized by JTAG or will not work.

Related FAQs
Does the Exposed Pad on the back side of the EQFP144 package of MAX® 10 require any connections?
https://www.macnica.co.jp/business/semiconductor/support/faqs/intel/122313/

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Category: Configuration/Programming
Tools:-
Device: MAX® 10