Verb tense shift when "never" or "ever" is used

Thank you again for answering all of my posts. I have posted this topic a couple of times because it has given me a lot of trouble. I have read all the comments made by some forum members. I have also discussed it quite a lot with my non-native English speaking friends. I know your time is valuable, and I am sorry to ask for further help. I think I am starting to understand the grammar related to this topic. To make sure that I really understand it, may I ask you to help me once more?

(1a) I have never been tricked while [...] shopping at ABC.

(2a) I have been tricked a few times while [...] shopping at ABC.

(3a) I was tricked a few times while [...] shopping at ABC.

(4a) Have you ever seen a tornado while [...] driving to work?

The brackets indicate that the words omitted are understood. If I choose to include them in the sentences, I will have the following changes.

(1b) I have never been tricked while I was shopping at ABC. (mixed tenses, okay)

(2b) I have been tricked a few times while I was shopping at ABC. (a tense mismatch, wrong)

(3b) I was tricked a few times while I was shopping at ABC. (a tense agreement, okay)

(4b) Have you ever seen a tornado while I was driving to work? (mixed tenses, okay)

(4c) Have you ever seen a tornado while I have been driving to work? (sounds awkward)

I have shown which ones I think are wrong and which ones I think are right. As I understand, "never" and "ever" allow a tense shift because these words indicate an event happening in the past, leading up to the present. So, it is okay to have mixed tenses (present perfect and simple past) in (1b) and (4b). (3b) is certainly correct because the simple past is used in the whole sentence. However, the mismatched tenses in (2b) make it grammatically wrong and the present perfect in the dependent clause of (4c) "while I have been..." makes it sound odd.

Like I said, I am not sure if I understand the grammar related to this topic fully. Please give me your final opinion. I am sure your final comments will improve my understanding further. After this, I will leave this topic. I really appreciate your valuable time and help. Many thanks.