Using Joomla 3.8.5 and CiviCRM 4.7.29. a membership transaction is entered in CiviCRM and paid via PayPal. The transaction completes in PayPal and an IPN is sent to CiviCRM. CiviCRM displays the thank-you page with transaction details, but in CiviCRM the payment remains in Pending status. The user gets a PayPal payment message, but no CiviCRM receipt. Note Paypal IPN log shows 200.
Checking the CiviCRM log file in the ConfigAndLog folder shows this sequence of events (identifying elements overwritten with XXX):
/home/XXX/public_html/libraries/src/Application/CMSApplication.php(303): Joomla\CMS\Application\SiteApplication->doExecute()
#16 /home/XXX/public_html/index.php(49): Joomla\CMS\Application\CMSApplication->execute()
#17 {main}
Feb 25 10:51:54 [info] $IDS Detector Details = Array
(
[0] => Array
(
[name] => cm
[value] => {"module":"contribute","contactID":"321","contributionID":70,"membershipID":"10","contributionPageID":"1"}
[page] => /index.php?option=com_civicrm&task=civicrm/contribute/transact&Itemid=527&_qf_ThankYou_display=1&qfKey=ec4624b8d9deeeba55b37c86128bc24d_9754&amt=497.32&cc=CAD&cm=%7B%22module%22%3A%22contribute%22%2C%22contactID%22%3A%22321%22%2C%22contributionID%22%3A70%2C%22membershipID%22%3A%2210%22%2C%22contributionPageID%22%3A%221%22%7D&item_name=321-70-Individual%20Adult%20Registration&st=Completed&tx=4VC971156C5483419
[userid] => XXX
[session] => XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX [ip] => XX.XX.XXX.48
[reaction] => 0
[impact] => 43
)
[1] => Array
(
[name] => IDS_request_uri
[value] => /index.php?option=com_civicrm&task=civicrm/contribute/transact&Itemid=527&_qf_ThankYou_display=1&qfKey=ec4624b8d9deeeba55b37c86128bc24d_9754&amt=497.32&cc=CAD&cm=%7B%22module%22%3A%22contribute%22%2C%22contactID%22%3A%22321%22%2C%22contributionID%22%3A70%2C%22membershipID%22%3A%2210%22%2C%22contributionPageID%22%3A%221%22%7D&item_name=321-70-Individual%20Adult%20Registration&st=Completed&tx=4VC971156C5483419
[page] => /index.php?option=com_civicrm&task=civicrm/contribute/transact&Itemid=527&_qf_ThankYou_display=1&qfKey=ec4624b8d9deeeba55b37c86128bc24d_9754&amt=497.32&cc=CAD&cm=%7B%22module%22%3A%22contribute%22%2C%22contactID%22%3A%22321%22%2C%22contributionID%22%3A70%2C%22membershipID%22%3A%2210%22%2C%22contributionPageID%22%3A%221%22%7D&item_name=321-70-Individual%20Adult%20Registration&st=Completed&tx=4VC971156C5483419
[userid] => XXX
[session] => XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
[ip] => XX.XX.XXX.48
[reaction] => 0
[impact] => 43
)
)