Chrome 70.0.3508.0 (Official build) canary (32-bit) 
Android 8.0.1 Pixel 2 Build OMP4.171019.021.Q1
Talkback 6.2.0.199837370 
Firefox Focus 6.0 Build#21861909 

Steps to repro:
# Enable TalkBack using volume key shortcut or using Settings > Accessibility 
# Invoke the local context menu by swiping up then right per the documentation: https://support.google.com/accessibility/android/answer/6007066?hl=en
# Select "characters" granularity. 
# In the Chrome Omnibox, type in a series of text. For example, "this is a bunch of text". You can also paste in this text. Make sure your focus is in the edit field and you are editing. 
# Invoke the local context menu, select the cursor control menu, and move cursor to the beginning of the edit field. 
# Invoke the local context menu again, cursor control, start selection mode
# Linear navigate to start to select characters. For example, swipe one finger from the left to the right anywhere onscreen to start selecting individual characters in the words this, is, etc. 
Expected: as each character is selected, TalkBack reads it back
Actual: TalkBack says nothing during selection but will read the last character in each word when you select it. So it will say nothing for t,h, and i but will read the character s. 

Does not reproduce in Firefox if you follow the steps above.