I've been learning English since I was six, then went to a British university, completed my degree and now I live and work in the UK. My proficiency level would be easily rated at C1/C2 level - I am completely fluent in both reading and writing.
And yet, I still find words in English that I simply don't know how to pronounce. I can give them a try, but unless I've heard someone else say them, I have no idea. That's a huge problem with English and I know that a lot of people who learn English as a their second language struggle with it.
I'm a native English speaker (Australian) and I find myself looking at a dictionary on average 5 times a day. Probably because of this, and an amateur passion for linguistics, I have a broader depth of knowledge on word definitions and pronunciations than most people I communicate with.
It's certainly not uncommon for native English speakers to have no idea how to pronounce a whole bunch of English words because they don't use them, so you're not alone there.
I always tell people: read with a dictionary and understand the pronunciation key! Or use an app or web dictionary that has a 'play' button.
Having said all of that, I don't know if it's a huge problem - most people get by fine with the words they know, and domain-specific words tend to be ones you learn in the field.
> I still find words in English that I simply don't know how to pronounce. I can give them a try, but unless I've heard someone else say them, I have no idea.
...and even that isn't much of a problem if other people supply the correct pronunciation in a fun happy helpful way, instead of the sneering or sarcastic manner often used.
I'm a native English speaker who started watching movies and TV shows with the English subtitles turned on about 5 years ago, and in that time have found dozens of word pairs I thought were different, having only heard/spoken one word and read/written the other, but they were actually the same word. Just an idea.
I'm an English native and find there are few people I meet with as extensive a vocabulary as I have (but I don't move in academic circles or anything). However I find that there are words I know and use but pronounce differently to the norm, that's because they're words I've learnt through reading and never actually heard spoken by others.
Can't think of any just now - insouciance is a word I've never heard anyone else speak, but I think I pronounce that one correctly. Hopefully I've conveyed well enough what I mean without example. Actually Linux is an example - used it for years before I met another user and then heard Linus tell me how I'd pronounced it wrong, slightly different as it's a [foreign] name, I digress.
And yet, I still find words in English that I simply don't know how to pronounce. I can give them a try, but unless I've heard someone else say them, I have no idea. That's a huge problem with English and I know that a lot of people who learn English as a their second language struggle with it.