Regarding the Migration Analyzer, we would like to tell you that there are some limit applied due to which it shows failed. You need to perform the below mentioned steps to check the analyzer again.
While performing the Migration Analyzer you will be having this window in between and some check points. Here you need to set all the fields to its maximum possible value (for example: if maximum file size is of 200 KB then you need to put 200 KB in the File Size limitation field) as showing in the screenshot below.
After doing so, perform the migration analyzer again and then see the results. Also if it shows failed for some items then it also reflect the message containing the reason of failure. Please refer to the screenshot below: