[BUG] How is network traffic monitored? Sometimes it doesn't detect anything

**Describe the bug**

I can be transferring huge amounts up and down and the network section for the correct interface (eth0) shows no traffic whatsover.

**To Reproduce**

Seems to happen about 40% of the time. Relaunching makes no difference.

**Expected behavior**

Sometimes it reports network traffic fine.

**Screenshots**

this is network traffic reported by netdata

this is network traffic reported by bashtop

**Info (please complete the following information):**
- Bashtop version: 0.9.24
- (Linux) Linux distribution and version: unraid
- (Linux) Data collection type (/proc or psutil): /proc
- Terminal used: webterminal and Secure Shell
- Font used: webterminal default and Source Code Pro
- Bash version, `bash --version` (version 4.4 or above is required): GNU bash, version 5.0.11(1)-release (x86_64-slackware-linux-gnu)
- Locales: output of `locale -v` LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE=C
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=