Underflow bit always high on v0.39

[lindsaySFS]

I'd like my software to inform me if there's ever an underflow event. So I was trying to figure out how to check it. I noticed in the release notes a couple of fixes related to this, so I made sure I updated to the latest release.

According to the register map the correct register is 0x88.

User Interface underflow. If set, indicates an underflow occurred during data transfer at the user interface (FIFO interface). Software must write a 0x1 to clear this register bit

But when I try to read it, it's always giving me a value of 1.

I've tried rebooting and checking before running any software, I've tried with and without my software running which should not be creating underflows, but may be every now and again (hence me checking).

I'm accessing the Pluto via SSH and running the following to check it:

echo 0x88 > /sys/kernel/debug/iio/iio:device3/direct_reg_access
cat /sys/kernel/debug/iio/iio:device3/direct_reg_access

Also running the following to clear it:

# echo "0x88 0x1" > /sys/kernel/debug/iio/iio:device3/direct_reg_access

(device3 is cf-ad9361-dds-core-lpc)

Am I doing anything wrong? Is this a real issue someone else can verify?