Can you submit a ticket (https://esupport.stardock.com/index.php?/Tickets/Submit) with the save game attached so we can take a look?  Thank you.  

Ticket #TAD-241-90444 opened.

By the way, this is what it looks like to me:

Here's the Arena from ImprovementDefs.xml:

<Improvement>
    <InternalName>Arena</InternalName>
    <DisplayName>Arena_Name</DisplayName>
    <ShortDescription>Arena_ShortDec</ShortDescription>
    <Description>Arena_Dec</Description>
    <Icon>Arena.png</Icon>
    <BuildIcon>Arena_Build.png</BuildIcon>
    <ListIcon>Arena_Icon.png</ListIcon>
    <ImprovementType>Approval</ImprovementType>
    <PlacementType>Approval</PlacementType>
 
    <!-- Stats -->
 
    <Stats>
      <EffectType>ManufacturingCost</EffectType>
      <Scope>Queue</Scope>
      <Target>
        <TargetType>Improvement</TargetType>
      </Target>
      <BonusType>Flat</BonusType>
      <Value>90</Value>
    </Stats>
 
    <Stats>
      <EffectType>GoodsAndServices</EffectType>
      <Target>
        <TargetType>Colony</TargetType>
      </Target>
      <BonusType>Flat</BonusType>
      <Value>8</Value>
    </Stats>
 
    <Stats>
      <EffectType>Maintenance</EffectType>
      <Target>
        <TargetType>Improvement</TargetType>
      </Target>
      <BonusType>Flat</BonusType>
      <Value>1</Value>
    </Stats>
 
    <!-- Triggers -->
 
    <!-- Level Effect Trigers -->
 
    <!-- Level Effect Stats -->
 
    <LevelEffectStats>
      <EffectType>GoodsAndServices</EffectType>
      <Target>
        <TargetType>Colony</TargetType>
      </Target>
      <BonusType>Flat</BonusType>
      <Value>1</Value>
    </LevelEffectStats>
 
    <!-- Adjacency Bonuses -->
 
    <NeighborBonuses>
      <GiveBonusToNeighborType>Approval</GiveBonusToNeighborType>
      <NeighborBonusValue>1</NeighborBonusValue>
    </NeighborBonuses>
 
    <NeighborBonuses>
      <GiveBonusToNeighborType>Influence</GiveBonusToNeighborType>
      <NeighborBonusValue>1</NeighborBonusValue>
    </NeighborBonuses>
 
    <!-- Prerequisites -->
 
    <Prerequ>
      <Techs>
        <Option>TournamentTech</Option>
      </Techs>
      <UpgradesFrom>FightingPit</UpgradesFrom>
    </Prerequ>
 
  </Improvement>

Arena.png, Arena_Build.png, and Arena_Icon.png in the Gfx folder looks like I think they should in Windows Explorer, and in photo viewer preview.

Thanks for the report.  We're looking into it now.

Me too. Oddly, it occurs for me in modded play but not on normal... but there'seems no code differences in  the relevant files (I even c&ped the building over).

To the OP - you using any mod's or game alterations, including using the planet wheel reactivation? It may be something to do with the way the game uses the docs directory

We have found the problem and will address it in a future update.  

I saw this awhile back and thought it was just my video card, glad someone reported it and even better that its fixed