In resources/views/clients/show.blade.php
Change
@if ($client->client_industry)
{{ $client->client_industry->name }}<br/>
@endif
@if ($client->client_size)
{{ $client->client_size->name }}<br/>
@endif
to
@if ($client->industry->name)
{{ $client->industry->name }}<br/>
@endif
@if ($client->size->name)
{{ $client->size->name }}<br/>
@endif