[General] iframe does not work in threads

[americanteam]

I have the following problem on 2 forums. Iframe codes are not executed.
In Mycode the iframe is set correctly.In the Mycode test bench it works successfully (Copying the same code from the publication where it does not work).
But when I look at the past post (the same iframe code above), now it doesn't show anything.
All this has happened, perhaps, after the last update.
I've even tried Mybb's default template but it doesn't work either.
Can somebody help me?
Mybb 1.8.29
PHP 7.1.33
MySQLi 5.7.36

Actually, no Mycode works in the posts made, although I have checked all 3 Mycodes on the benchmark, they are working fine. But in the same posts made by users they don't work.
What can be?

[Crazycat]

If your forum is in https and the iframe source in http, it could be blocked.
If not, can you provide a link to your test post ? (and an account if required)

[americanteam]

If your forum is in https and the iframe source in http, it could be blocked.
If not, can you provide a link to your test post ? (and an account if required)

Actually, no Mycode works in the posts made, although I have checked all 3 Mycodes on the benchmark, they are working fine. What can be?
Mybb 1.8.29 
PHP 7.1.33
MySQLi 5.7.36

[Matt]

What do you mean by "no mycode works"? It doesn't parse it, or the message is empty? Is it this issue? https://docs.mybb.com/1.8/faq/errors/#pa...ion-failed

[americanteam]

What do you mean by "no mycode works"? It doesn't parse it, or the message is empty? Is it this issue? https://docs.mybb.com/1.8/faq/errors/#pa...ion-failed

the message is empty, in all the posts where they worked correctly before.

[Matt]

Okay, you'll need to follow the steps in that linked help doc to resolve.

[americanteam]

If your forum is in https and the iframe source in http, it could be blocked.
If not, can you provide a link to your test post ? (and an account if required)

This is a link where the problem is verified with an empty message.

shorturl.at/dDQ

user:test
pass: usernew

[Crazycat]

The link goes nowhere. Can you give the real link to your post please ?

[americanteam]

The link goes nowhere. Can you give the real link to your post please ?

sorry for that, I will never trust that shortener again.
user:test

pass: usernew

[Matt]

As above, you'll need to follow these steps to identify the cause: https://docs.mybb.com/1.8/faq/errors/#pa...ion-failed