Cannot extract the embedded font '55f416+Martel-Bold'. Some characters may not display or print...

Cannot extract the embedded font '55f416+Martel-Bold'. Some characters may not display or print correctly.

Hi @36104460

I get this issue when open my pdf by Adobe Acrobat. 
Consequently, some characters are not displayed:

Question #1: Did something change in Adobe Acrobat regarding the requirements for embedded fonts?

Question #2: Is there anything we can do to check whether our font meets all requirements?
How I embed fonts into pdf is shown here
font_families.update(
'Martel' => {
normal: 'fonts/Martel/Martel-Regular.ttf',
bold: 'fonts/Martel/Martel-Bold.ttf',
light: 'fonts/Martel/Martel-Light.ttf',
})
Thanks