Watchdog expires even in maximum SCLK0_0 cycles


I'm working in the customer project.
We have a requirement to configure WatchDog Timer in the project.
Currently, we are facing issue in setting the WatchDog Timer Count.

For WatchDog evaluation, the issue is simulated in EZKIT 21569.
I have explained the issue details below.

Kindly support us to proceed further.

Hardware Setup:
EZKIT- 21569 UL (actual - ADSP21563)
CCES - 2.9.1

Overview of the source code:
SportCallback ISR
      - Receive and transmit data for 32(16*2) samples through SPORT DMA.
Main Processing - 256(128*2) samples.
Reset WDT after every frame processed.

Cycles consumed:
      max - 6913
      min - 4636

Default Clock Configuration:
Core clock - 1000MHz (actual - 600MHz)
SCLK0 - 125 MHz (actual - 75 MHz)

Case1 :
Configure WDT Counter as 1000. (Approx. Max cycles/8)
At this time, WDT expires.

Case 2:
Configure WDT Counter as 3,33,333. (SCLK0_0 cycles).
At this time, WDT Expires

Case 3:
Configure WDT Counter as 3,93,215‬. (greater than SCLK0 cycles).
No WDT expiration

Kindly provide details on what basis WDT Counter value is set?
Is there any impact possible on watchdog counter value because of SPORT ISR callback?
Attached the evaluation code for reference.

Thanks and Regards,