Board is not functioning anymore after pio update

Here’s the story:
I am currently making a project involving multithreading, hence I tried installing the mbed library with “pio lib install mbed” for my Arduino Nano 33 BLE board (I later realized I didn’t have to do that, and the install failed anyways). I also ran “pio run --target clean” after the installation of mbed failed the first time.
After that, it still failed! So I ran “pio platform update” and “pio pkg update”. After the installation of the mbed library still failing, I gave up, moved on, and figured out that I didn’t need to install it in the first place!

Now here comes the problem:
After I was happy with my code and hit upload … nothing. The board didn’t seem to run at all anymore. I thought there was something wrong with my code, but after reverting it back to the old version before any of the newest changes … still, nothing.
I then confirmed my suspicion when I tried uploading another sketch to a different board, and this new board stopped functioning as well - something is wrong.

I have to go into dev-mode on the boards by pressing the reset button twice to even get them to list under “/dev/tty…”. What a mess.

After a lot of googling, I couldn’t find anyone with a similar problem.
I thought that it might have had something to do with me using an older version of pio beforehand, and so I already tried installing an older version with “pip install -U platformio=x.x.x”, but then there was an error for multiple pio-cores, after which I abandoned that idea. I couldn’t tell you which version I was on before anyways.

My platformio.ini looks as follows:

; PlatformIO Project Configuration File
;   Build options: build flags, source filter
;   Upload options: custom upload port, speed and extra flags
;   Library options: dependencies, extra library storages
;   Advanced options: extra scripting
; Please visit documentation for the other options and examples

platform = nordicnrf52
board = nano33ble
framework = arduino
monitor_speed = 9600
lib_deps = 

Best regards, Philip