How to fix
Find the code:
Replace it with the following one:
<container name="content.top" label="Main Content Top" before="-"/>
Find the code:
Replace it with the following one:
<container name="content.top" label="Main Content Top" before="-"/>
This wrong system bevahiour is caused by the same Magento 2 core bug as here: How top fix the «Invalid method Magento\Customer\Block\Account\Navigation::removeLinkByUrl» bug
Try
<move element="page.main.title" destination="content" before="-"/>
in \app\design\frontend\THEME\default\Magento_Customer\layout\customer_account.xml
This issue is already fixed in Magento 2 9 months ago: