FT857D opcodes not executing because of Digirig?

Working with sending OPCODES to a FT857D (Windows 10 machine) using a external program to send commands to the radio.
I send Opcode Hex 0a 00 00 00 07 to set Digital mode, send the traffic (PTTon/off) and then send the Hex 01 00 00 00 07 to reset back to USB.
I was told the reason the return back to USB does not work is because DIGIRIG controls the execution? They send this explanation (See below). I find this hard to believe,

The program does executes the 0A (DIG), then PTTon then PTToff, but will not execute the last command?
So I guess I am trying to get confirmation that DIGIRIG does not control the execution of commands, It just acts as the interface between the program and the radio.

Duplex serial CAT with logic levels

We find this option in mid-grade modern rigs like Yaesu’s FT-8xx series and Xiegu. This interface features distinct TxD and RxD serial port lines which operate at a logical level of 3.3V. Typically the command set includes all of the radio’s controls including VFO, band selection, preamps, tuner and most importantly transmit command. Paired with the Middleware Software such as FlRig it allows operator to fully control the radio from PC and opens good potential for remote operation.

This is the default Digirig configuration and it is supported by the interface from the very first revision.

I do not own that radio, and I am not sure what the question is. FWIW, I used flrig, Digirig (logic levels) and truSDX to send CAT commands in hex and receive responses. There is an XML definition file somewhere in fldigi for the CAT commands for each radio.

If commands are not executing after PTT, there may be an RFI issue. You can go step-by-step using this guide, Troubleshooting Digital Modes – digirig.

73 Constrainted

When it comes to the serial port traffic, Digirig is oblivious to what passes through, it just facilitates the transfer without parsing, trying to understand or modifying anything. This allows it to be used for CAT control, programming of the radios, programming Arduinos, connecting old school serial mice or anything else related to traditional serial ports.

As @Constrainted pointed out, if the only time the commands fail is after/during PTT then there is a possibility of RF power disrupting the serial communication.