I understand that frontal lobe seizures do not show on eeg due to skull thickness and those deep in the brain are too far away. is this correct?

Yes: This may be true. Some frontal lobe seizures may be diagnosed by video alone (when typical), even when the eeg does not show typical changes consistent with seizure. This is true with a deep frontal focus, or when the seizures are so violent that the eeg may not be interpreted. Other frontal lobe seizures may be visible on surface eeg.

Sometimes true: Sometimes, frontal lobe seizures show on surface (regular eeg). However, at other times, the focus may be too far away (e.g. In the inner part of the frontal lobe). In such cases, your neurologist may consider a surgical procedure in which electrodes are placed inside the skull closer to the surface of the brain for recording (they are called subdural electrodes).