Which problem is illustrated by the following sentence?

I joined the others by the fire however they were about to go to bed.

improper use of voice

wordiness

unclear meaning

grammatically incorrect

The sentence has incomplete punctuation marks, making it grammatically incorrect.

It sounds better if it is written this way:

'I joined the others by the fire, however, they were about to go to bed.'

Due to the incomplete punctuation marks, it created an unclear meaning.