Whilst it doesn't seem to have any effect on the records submitted, I sometimes get an error message after having submitted them. As it's happened a few times, I thought it might be worth flagging, just in case!
Warning: file_get_contents(modules/custom/iform/client_helpers/prebuilt_forms/css\two-col.css): Failed to open stream: No such file or directory in DrupaNCore Asset\CssCollectionOptimizerLazy->generateHash| (line 43 of core/lib/Drupal/Core/Asset/AssetGroupSetHashTrait php).
Drupal\Core\Asset\CssCollectionOptimizerLazy->generateHash() (Line: 120)
Drupal\Core\Asset\CssCollectionOptimizerLazy->optimize() (Line: 231)
Drupal\Core\Asset\AssetResolver->getCssAssets) (Line: 323)
Drupal\Core\Render\HtmlResponseAttachmentsProcessor->processAssetLibraries() (Line: 167)
Drupal\Core\Render\HtmlResponseAttachmentsProcessor->processAttachments() (Line: 45)
Drupal\Core\EventSubscriber\HtmlResponseSubscriber->onRespond()
call_user_func() (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch() (Line: 214)
Symfony\Component\HttpKernel\HttpKernel->filterResponse() (Line: 202)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 76)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 32)
Drupal\iform\Middleware\Redirect->handle() (Line: 68)
Drupal\simple_oauth\HttpMiddleware\BasicAuthSwap->handle() (Line: 53)
Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 28)
Drupal\Core\StackMiddleware\ContentLength->handle() (Line: 116)
Drupal\page_cache\StackMiddleware\PageCache >pass() (Line: 90)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 53)
Asm89\Stack\Cors->handle() (Line: 50)
Drupal\ban\BanMiddleware->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware >handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware >handle() (Line: 36)
Drupal\Core\StackMiddleware\AjaxPageState >handle() (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 741)
Drupal\Core\DrupalKernel->handle() (Line: 19)