from mainly old posts.
There are several reasons why this is happening:
1) Dead image/download link(s)
2) The O/P contains dead link(s), and when deleted, all responses are automatically deleted as well.
However, if responses include images, then that post, and any subsequent posts are made into a new thread
3) Since merging threads has to be done one (1) post at a time (6 (no notification) to 8 (with notification) steps for each O/P; 1 for each response post), it takes a lot of time to do. So, if a thread is more than 3 pages (60 posts), then only relevant (image, verified links and select + comments) posts are merged
4) Back to back posts ("oops, forgot to post this"; not including those with 11+ attachments) in the same thread
Also, in most cases, only the O/P should receive an Alert stating the cause.
There are several reasons why this is happening:
1) Dead image/download link(s)
2) The O/P contains dead link(s), and when deleted, all responses are automatically deleted as well.
However, if responses include images, then that post, and any subsequent posts are made into a new thread
3) Since merging threads has to be done one (1) post at a time (6 (no notification) to 8 (with notification) steps for each O/P; 1 for each response post), it takes a lot of time to do. So, if a thread is more than 3 pages (60 posts), then only relevant (image, verified links and select + comments) posts are merged
4) Back to back posts ("oops, forgot to post this"; not including those with 11+ attachments) in the same thread
Also, in most cases, only the O/P should receive an Alert stating the cause.