ATMEGA328P-AU can program via SPI but not via UART

[seamaster]

Hello,
I did do quite a bit of searches before decided to post my problem. I tried in many different ways, but ultimately couldn't get custom Atmega board to program with serial programmer.
my board has 8MHz external crystal, and operates on 3.3V.
here is the schematic

here is the sequence of events:
First I programmed one Arduino Uno board with ArduinoISP example.
and I installed micro-core in board manager.
Second I connected my new board via the ICSP pins to the programmed as ISP Uno board.
then I switch the programmer mode to "Arduino as ISP"
then I made the following selections:

next I selected "burn bootloader"
the bootloader was updated succesfuly
Next I loaded "blink without delay.ino" and uploaded it by selecting sketch-> "upload via programer" (Arduino as ISP). that also worked fine and the LED that I attached on pin 13 start blinking.
So far so good - I can program the board via ICSP (SPI).
Next I tried to connect serial TTL programer to the TX and RX on my new board. I'm not new at this and I'm sure Iconnected them right, but JIC I also reversed them. I also connected the Reset to RTS on the serial programmer. then tried to flash by selecting "AVRISP MkII". It did not work. I can see the Tx LED on the programer flashing from time to time and trying to initialize communication, but my new board dot appears to communicate.
Then I tried using the UNO board as serial programmer. Same result. Again, the AVR DUDE SW retries 10 times to establish communication and then quits.
So mu question is why? Did I miss something? is there some fuse that needs to be burned somehow to enable me to program the ATMEGA 328P_AU chip via UART?

Thank you in advance for your help!
Cheers

[seamaster]

I solved the problem thanks to a post that I found here on this forum! posted few minutes before I did post this one.
https://forum.arduino.cc/index.php?topic=733723.0
the issue was that i programmed the Blink.ino with the SPI for the initial test after successfully burning the bootloader that i tried to upload again via UART.
in the post I read here someone explained that when you flash the *.ino file via the SPI interface it also overwrite the bootloader, therefore on further attempts to do it via UART, I was unsuccessful as there was no bootloader left on the chip.

The roper sequence is:
First, upload the Bootloader as described in my initial post
Second switch the programming interface to USB/UART interface and the programer type back to AVRISP or AVRISP MrkII and upload test code. Surpise! it works, and has been working ever since. it only took 2 days...
Not sure how to mark the issue as solved. if moderator could do that, please do!

Cheers everyone and happy arduinoing!