I seem to have the same issue with 2.0.3. The first upload after restart of the IDE works in the sense that the code gets uploaded to the Pico, but the IDE does not seem to recognize that the upload is finished and so the "progress animation" just keeps on scrolling around forever:
Here is the output of the verbose upload log:
Sketch uses 56180 bytes (2%) of program storage space. Maximum is 2093056 bytes.
Global variables use 7548 bytes (2%) of dynamic memory, leaving 254596 bytes for local variables. Maximum is 262144 bytes.
"C:\Users\Per\AppData\Local\Arduino15\packages\rp2040\tools\pqt-python3\1.0.1-base-3a57aed/python3" -I "C:\Users\Per\AppData\Local\Arduino15\packages\rp2040\hardware\rp2040\2.6.5/tools/uf2conv.py" --serial "UF2_Board" --family RP2040 --deploy "C:\Users\Per\AppData\Local\Temp\arduino-sketch-C3A1E98DCB6061CC6BF6CD9084F2FFAC/144m_Si5351.ino.uf2"
Converting to uf2, output size: 142848, start address: 0x2000
Flashing G: (RPI-RP2)
Wrote 142848 bytes to G:/NEW.UF2
I think it says that all is fine, but as I mentioned, the "progress animation" just keeps saying that "Uploading..." is still in progress and I am therefore unable to upload again until I restart the IDE. Other functions, like verifying code, still works in this state. The port changed from UF2 to COM8 during the upload. Unplugging the Pico does not have any effect on the persistent progress bar.